New Prespective Paleogeography of East Java Basin; Implicationrespond to Oil and Gas Eksploration at Kujung Formation Carbonate Reservoar

NASA Astrophysics Data System (ADS)

Aprilana, C.; Premonowati; S, Hanif I.; Choirotunnisa; Shirly, A.; Utama, M. K.; Sinulingga, Y. R.; Syafitra, F.

2018-03-01

Paleogeography is one of critical points that always less considered by explorationist in the world. Almost all of the consideration is focused on trapping mechanism. Paleogeography is guidance in understanding both of physical and chemical of rock characteristic which will correlate with its depositional environment. Integration of various geological and geophysical data such as; tectonic, structural geology, stratigraphy, lithology, and biostratigraphy will lead us to a better understanding of rock characteristics. Six paleogeographic interpretations was made consist of; Early Tertiary (P5-56-55 ma), Middle Eocene (P14-41 ma), Late Oiligocene (P22-25.5 ma), Early Miocene (N7-16.5 ma), Middle Miocene (N9-14.5 ma), and Pleistocene (NN19-1.5 ma). That six paleogeographic interpretations are assumed represent the paleogeographic evolution of East Java Basin time after time. In Middle Eocene time, it would be more than hundred possibilities regarding the location where the formation deposited. This would be controlled by the existence of some local structural paleohighs and horsts which oriented NW-SE followed by their own sedimentary transportation path. With assumption that hydrocarbon generation was occurred in 15 Ma and the depth of maturation window lies on about 2,500 m depth. Therefore, the possibility of source rock maturation is high, due to almost of the clastics sediment of Ngimbang deposited into the series of grabens. The Kujung reef types simplified defines and categorize into; 1) Patch Reef 2) Berrier Reef 3) Pinnacle Reef Over Isolated Reef. Kujung Carbonates were deposited in Early Miocene when regional transgression occurred. The depositional environments were dominated by shallow marine littoral-sublittoral. Generally, the reservoir quality of this Kujung Carbonate shows fair to good quality, in range7-32% porosity, and 1-1400 mD permeability (internal SKK Migas data).

Oligocene and Early Miocene coral faunas from Iran: palaeoecology and palaeobiogeography

NASA Astrophysics Data System (ADS)

Schuster, F.; Wielandt, U.

Oligocene and Early Miocene coral assemblages from three sections of central Iran are investigated with respect to their palaeoecological and palaeobiogeographic implications. These corals are compared with faunas from the Mediterranean Tethys and the Indopacific. Associated larger foraminifers are used for biostratigraphy and to support the palaeoecological interpretation. The studied sections are situated in the foreland basins of the Iranian Plate which is structured into a fore-arc and a back-arc basin separated by a volcanic arc. The coral assemblages from Abadeh indicate a shallowing-upward trend. Infrequently distributed solitary corals at the base of the section indicate a turbid environment. Above, a distinct horizon characterised by a Leptoseris-Stylophora assemblage associated with lepidocyclinids and planktonic foraminifers is interpreted as maximum flooding surface. Small patch reefs with a Porites-Faviidae assemblage are a common feature of Late Oligocene to Early Miocene coral occurrences and indicate water depths of less than 20m. The diversity of the coral faunas shows marked differences. Oligocene corals from the Esfahan-Sirjan fore-arc basin comprise more than 45 species of 32 genera and occur in a wide range of environments. Early Miocene corals from the Qom back-arc basin are less frequent, show a lower diversity (13 genera with 15 species) and occur in single horizons or small patch reefs.

Neogene reef coral assemblages of the Bocas del Toro region, Panama: the rise of Acropora palmata

NASA Astrophysics Data System (ADS)

Klaus, J. S.; McNeill, D. F.; Budd, A. F.; Coates, A. G.

2012-03-01

Temporal patterns are evaluated in Neogene reef coral assemblages from the Bocas del Toro Basin of Panama in order to understand how reef ecosystems respond to long-term environmental change. Analyses are based on a total of 1,702 zooxanthellate coral specimens collected from six coral-bearing units ranging in age from the earliest Late Miocene to the Early Pleistocene: (1) Valiente Formation (12-11 Ma), (2) Fish Hole Member of the Old Bank Formation (5.8-5.6 Ma), (3) La Gruta Member of the Isla Colon Formation (2.2-1.4 Ma), (4) Ground Creek Member of the Isla Colon Formation (2.2-1.4 Ma), (5) Mimitimbi Member of the Urracá Formation (1.2-0.8 Ma), and (6) Hill Point Member of the Urracá Formation (1.2-0.8 Ma). Over 100 coral species occur in the six units, with faunal assemblages ranging from less than 10% extant taxa (Valiente Formation) to over 85% extant taxa (Ground Creek Member). The collections provide new temporal constraints on the emergence of modern Caribbean reefs, with the La Gruta Member containing the earliest occurrence of large monospecific stands of the dominant Caribbean reef coral Acropora palmata, and the Urracá Formation containing the last fossil occurrences of 15 regionally extinct taxa. Canonical correspondence analysis of 41 Late Miocene to Recent reef coral assemblages from the Caribbean region suggests changes in community structure coincident with effective oceanic closure of the Central American Seaway (~3.5 Ma). These changes, including increased Acropora dominance, may have contributed to a protracted period of elevated extinction debt prior to the major peak in regional coral extinctions (~2-1 Ma).

Miocene transgression in the central and eastern parts of the Sivas Basin (Central Anatolia, Turkey) and the Cenozoic palaeogeographical evolution

NASA Astrophysics Data System (ADS)

Poisson, André; Vrielynck, Bruno; Wernli, Roland; Negri, Alessandra; Bassetti, Maria-Angela; Büyükmeriç, Yesim; Özer, Sacit; Guillou, Hervé; Kavak, Kaan S.; Temiz, Haluk; Orszag-Sperber, Fabienne

2016-01-01

We present here a reappraisal of the tectonic setting, stratigraphy and palaeogeography of the central part of the Sivas Basin from Palaeocene to late Miocene. The Sivas Basin is located in the collision zone between the Pontides (southern Eurasia) and Anatolia (a continental block rifted from Gondwana). The basin overlies ophiolites that were obducted onto Anatolia from Tethys to the north. The Central Anatolian Crystalline Complex (CACC) experienced similar ophiolite obduction during Campanian time, followed by exhumation and thrusting onto previously emplaced units during Maastrichtian time. To the east, crustal extension related to exhumation of the CACC created grabens during the early Tertiary, including the Sivas Basin. The Sivas Basin underwent several tectonic events during Paleogene-Neogene. The basin fill varies, with several sub-basins, each being characterised by a distinctive sequence, especially during Oligocene and Miocene. Evaporite deposition in the central part of the basin during early Oligocene was followed by mid-late Oligocene fluvio-lacustrine deposition. The weight of overlying fluvial sediments triggered salt tectonics and salt diapir formation. Lacustrine layers that are interbedded within the fluviatile sediments have locally yielded charophytes of late Oligocene age. Emergent areas including the pre-existing Sivas Basin and neighbouring areas were then flooded from the east by a shallow sea, giving rise to a range of open-marine sub-basins, coralgal reef barriers and subsiding, restricted-marine sub-basins. Utilising new data from foraminifera, molluscs, corals and nannoplankton, the age of the marine transgression is reassessed as Aquitanian. Specifically, age-diagnostic nannoplankton assemblages of classical type occur at the base of the transgressive sequence. However, classical stratigraphic markers have not been found within the planktic foraminiferal assemblages, even in the open-marine settings. In the restricted-marine sediments, there are rich planktic foraminiferal assemblages of classical type but these are of little use in stratigraphy. In contrast, the gastropod fauna indicate a Burdigalian age. Sediment reworking in the restricted-marine environments precludes stratigraphic determination. In such environments, micro- and nano-organisms experienced atypical developmental conditions. The small benthic foraminifera and associated ostracod assemblages are good indicators of salinity which varied considerably within the restricted-marine sub-basins. Some of the corals within the coralgal reefs barriers are also dated as Aquitanian. A combination of the salt tectonics and the late Miocene north-westward-verging thrusting created the present basin complexity.

Plate tectonics drive tropical reef biodiversity dynamics

PubMed Central

Leprieur, Fabien; Descombes, Patrice; Gaboriau, Théo; Cowman, Peter F.; Parravicini, Valeriano; Kulbicki, Michel; Melián, Carlos J.; de Santana, Charles N.; Heine, Christian; Mouillot, David; Bellwood, David R.; Pellissier, Loïc

2016-01-01

The Cretaceous breakup of Gondwana strongly modified the global distribution of shallow tropical seas reshaping the geographic configuration of marine basins. However, the links between tropical reef availability, plate tectonic processes and marine biodiversity distribution patterns are still unknown. Here, we show that a spatial diversification model constrained by absolute plate motions for the past 140 million years predicts the emergence and movement of diversity hotspots on tropical reefs. The spatial dynamics of tropical reefs explains marine fauna diversification in the Tethyan Ocean during the Cretaceous and early Cenozoic, and identifies an eastward movement of ancestral marine lineages towards the Indo-Australian Archipelago in the Miocene. A mechanistic model based only on habitat-driven diversification and dispersal yields realistic predictions of current biodiversity patterns for both corals and fishes. As in terrestrial systems, we demonstrate that plate tectonics played a major role in driving tropical marine shallow reef biodiversity dynamics. PMID:27151103

Plate tectonics drive tropical reef biodiversity dynamics.

PubMed

Leprieur, Fabien; Descombes, Patrice; Gaboriau, Théo; Cowman, Peter F; Parravicini, Valeriano; Kulbicki, Michel; Melián, Carlos J; de Santana, Charles N; Heine, Christian; Mouillot, David; Bellwood, David R; Pellissier, Loïc

2016-05-06

The Cretaceous breakup of Gondwana strongly modified the global distribution of shallow tropical seas reshaping the geographic configuration of marine basins. However, the links between tropical reef availability, plate tectonic processes and marine biodiversity distribution patterns are still unknown. Here, we show that a spatial diversification model constrained by absolute plate motions for the past 140 million years predicts the emergence and movement of diversity hotspots on tropical reefs. The spatial dynamics of tropical reefs explains marine fauna diversification in the Tethyan Ocean during the Cretaceous and early Cenozoic, and identifies an eastward movement of ancestral marine lineages towards the Indo-Australian Archipelago in the Miocene. A mechanistic model based only on habitat-driven diversification and dispersal yields realistic predictions of current biodiversity patterns for both corals and fishes. As in terrestrial systems, we demonstrate that plate tectonics played a major role in driving tropical marine shallow reef biodiversity dynamics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saller, A.H.; Schlanger, S.O.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1,000 m of upper eocene, Oligocene, and lower Miocene carbonates. STrontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids(.), and minor planktonicmore » forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic are abundant in fore-reef, reef, and some back-reef strata). Petrographic and geochemical data indicate arogonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates.« less

A unique coral biomineralization pattern has resisted 40 million years of major ocean chemistry change

NASA Astrophysics Data System (ADS)

Stolarski, Jarosław; Bosellini, Francesca R.; Wallace, Carden C.; Gothmann, Anne M.; Mazur, Maciej; Domart-Coulon, Isabelle; Gutner-Hoch, Eldad; Neuser, Rolf D.; Levy, Oren; Shemesh, Aldo; Meibom, Anders

2016-06-01

Today coral reefs are threatened by changes to seawater conditions associated with rapid anthropogenic global climate change. Yet, since the Cenozoic, these organisms have experienced major fluctuations in atmospheric CO2 levels (from greenhouse conditions of high pCO2 in the Eocene to low pCO2 ice-house conditions in the Oligocene-Miocene) and a dramatically changing ocean Mg/Ca ratio. Here we show that the most diverse, widespread, and abundant reef-building coral genus Acropora (20 morphological groups and 150 living species) has not only survived these environmental changes, but has maintained its distinct skeletal biomineralization pattern for at least 40 My: Well-preserved fossil Acropora skeletons from the Eocene, Oligocene, and Miocene show ultra-structures indistinguishable from those of extant representatives of the genus and their aragonitic skeleton Mg/Ca ratios trace the inferred ocean Mg/Ca ratio precisely since the Eocene. Therefore, among marine biogenic carbonate fossils, well-preserved acroporid skeletons represent material with very high potential for reconstruction of ancient ocean chemistry.

Hydrocarbons in New Guinea, controlled by basement fabric, Mesozoic extension and Tertiary convergent margin tectonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, K.C.; Kendrick, R.D.; Crowhurst, P.V.

1996-01-01

Most models for the tectonic evolution of New Guinea involve Early and Late Miocene arc-continent collisions, creating an orogenic belt. Structural trends and prospectivity are then analyzed in terms of belts across the country; the Fold Belt (with the discovered oil and gas fields), the Mobile Belt and the accreted arcs. This model inhibits realistic assessment of prospectivity. It now appears the Mobile Belt formed by Oligocene compression then by Early Miocene extension, related to slab-rollback, that unroofed metamorphic core complexes adjacent to starved half-grabens. The grabens filled in the Middle Miocene and were largely transported intact during the Pliocenemore » arc-collision. Early Miocene reefs and hypothesized starved basin source rocks create a viable play throughout northern New Guinea as in the Salawati Basin. The Pliocene clastic section is locally prospective due to overthrusting and deep burial. Within the Fold Belt, the site and types of oil and gas fields are largely controlled by the basement architecture. This controlled the transfer zones and depocentres during Mesozoic extension and the location of major basement uplifts during compression. In PNG, the Bosavi lineament separates an oil province from a gas province. In Irian Jaya the transition from a relatively competent sequence to a rifted sequence west of [approx]139[degrees]E may also be a gas-oil province boundary. Understanding, in detail, the compartmentalization of inverted blocks and areas of thin-skinned thrusting, controlled by the basement architecture, will help constrain hydrocarbon prospectivity.« less

Hydrocarbons in New Guinea, controlled by basement fabric, Mesozoic extension and Tertiary convergent margin tectonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, K.C.; Kendrick, R.D.; Crowhurst, P.V.

1996-12-31

Most models for the tectonic evolution of New Guinea involve Early and Late Miocene arc-continent collisions, creating an orogenic belt. Structural trends and prospectivity are then analyzed in terms of belts across the country; the Fold Belt (with the discovered oil and gas fields), the Mobile Belt and the accreted arcs. This model inhibits realistic assessment of prospectivity. It now appears the Mobile Belt formed by Oligocene compression then by Early Miocene extension, related to slab-rollback, that unroofed metamorphic core complexes adjacent to starved half-grabens. The grabens filled in the Middle Miocene and were largely transported intact during the Pliocenemore » arc-collision. Early Miocene reefs and hypothesized starved basin source rocks create a viable play throughout northern New Guinea as in the Salawati Basin. The Pliocene clastic section is locally prospective due to overthrusting and deep burial. Within the Fold Belt, the site and types of oil and gas fields are largely controlled by the basement architecture. This controlled the transfer zones and depocentres during Mesozoic extension and the location of major basement uplifts during compression. In PNG, the Bosavi lineament separates an oil province from a gas province. In Irian Jaya the transition from a relatively competent sequence to a rifted sequence west of {approx}139{degrees}E may also be a gas-oil province boundary. Understanding, in detail, the compartmentalization of inverted blocks and areas of thin-skinned thrusting, controlled by the basement architecture, will help constrain hydrocarbon prospectivity.« less

Fifty million years of herbivory on coral reefs: fossils, fish and functional innovations

PubMed Central

Bellwood, D. R.; Goatley, C. H. R.; Brandl, S. J.; Bellwood, O.

2014-01-01

The evolution of ecological processes on coral reefs was examined based on Eocene fossil fishes from Monte Bolca, Italy and extant species from the Great Barrier Reef, Australia. Using ecologically relevant morphological metrics, we investigated the evolution of herbivory in surgeonfishes (Acanthuridae) and rabbitfishes (Siganidae). Eocene and Recent surgeonfishes showed remarkable similarities, with grazers, browsers and even specialized, long-snouted forms having Eocene analogues. These long-snouted Eocene species were probably pair-forming, crevice-feeding forms like their Recent counterparts. Although Eocene surgeonfishes likely played a critical role as herbivores during the origins of modern coral reefs, they lacked the novel morphologies seen in modern Acanthurus and Siganus (including eyes positioned high above their low-set mouths). Today, these forms dominate coral reefs in both abundance and species richness and are associated with feeding on shallow, exposed algal turfs. The radiation of these new forms, and their expansion into new habitats in the Oligocene–Miocene, reflects the second phase in the development of fish herbivory on coral reefs that is closely associated with the exploitation of highly productive short algal turfs. PMID:24573852

Fifty million years of herbivory on coral reefs: fossils, fish and functional innovations.

PubMed

Bellwood, D R; Goatley, C H R; Brandl, S J; Bellwood, O

2014-04-22

The evolution of ecological processes on coral reefs was examined based on Eocene fossil fishes from Monte Bolca, Italy and extant species from the Great Barrier Reef, Australia. Using ecologically relevant morphological metrics, we investigated the evolution of herbivory in surgeonfishes (Acanthuridae) and rabbitfishes (Siganidae). Eocene and Recent surgeonfishes showed remarkable similarities, with grazers, browsers and even specialized, long-snouted forms having Eocene analogues. These long-snouted Eocene species were probably pair-forming, crevice-feeding forms like their Recent counterparts. Although Eocene surgeonfishes likely played a critical role as herbivores during the origins of modern coral reefs, they lacked the novel morphologies seen in modern Acanthurus and Siganus (including eyes positioned high above their low-set mouths). Today, these forms dominate coral reefs in both abundance and species richness and are associated with feeding on shallow, exposed algal turfs. The radiation of these new forms, and their expansion into new habitats in the Oligocene-Miocene, reflects the second phase in the development of fish herbivory on coral reefs that is closely associated with the exploitation of highly productive short algal turfs.

Constraining controls on carbonate sequences with high-resolution chronostratigraphy: Upper Miocene, Cabo de Gata region, SE Spain

USGS Publications Warehouse

Montgomery, P.; Farr, M.R.; Franseen, E.K.; Goldstein, R.H.

2001-01-01

A high-resolution chronostratigraphy has been developed for Miocene shallow-water carbonate strata in the Cabo de Gata region of SE Spain for evaluation of local, regional and global factors that controlled platform architecture prior to and during the Messinian salinity crisis. Paleomagnetic data were collected from strata at three localities. Mean natural remanent magnetization (NRM) ranges between 1.53 ?? 10-8 and 5.2 ?? 10-3 Am2/kg. Incremental thermal and alternating field demagnetization isolated the characteristic remanent magnetization (ChRM). Rock magnetic studies show that the dominant magnetic mineral is magnetite, but mixtures of magnetite and hematite occur. A composite chronostratigraphy was derived from five stratigraphic sections. Regional stratigraphic data, biostratigraphic data, and an 40Ar/39Ar date of 8.5 ?? 0.1 Ma, for an interbedded volcanic flow, place the strata in geomagnetic polarity Chrons C4r to C3r. Sequence-stratigraphic and diagenetic evidence indicate a major unconformity at the base of depositional sequence (DS)3 that contains a prograding reef complex, suggesting that approximately 250 000 yr of record (Subchrons C3Br.2r to 3Br.1r) are missing near the Messinian-Tortonian boundary. Correlation to the GPTS shows that the studied strata represent five third- to fourth-order DSs. Basal units are temperate to subtropical ramps (DS1A, DS1B, DS2); these are overlain by subtropical to tropical reefal platforms (DS3), which are capped by subtropical to tropical cyclic carbonates (Terminal Carbonate Complex, TCC). Correlation of the Cabo de Gata record to the Melilla area of Morocco, and the Sorbas basin of Spain indicate that early - Late Tortonian ramp strata from these areas are partially time-equivalent. Similar strata are extensively developed in the Western Mediterranean and likely were influenced by a cool climate or influx of nutrients during an overall rise in global sea-level. After ramp deposition, a sequence boundary (SB3) in Cabo de Gata correlates with a sequence boundary in Morocco and a published third-order eustatic fall suggesting at least a partial eustatic control for the sequence boundary. Coral reefs began to develop earlier in Cabo de Gata than at Melilla or Sorbas, arguing for local factors affecting this major environmental transition. Later Messinian reefs (DS3) from all areas are time-equivalent, suggesting a regional or global control on their formation. Some Halimeda-rich horizons in the Western Mediterranean are not time-equivalent event strata as hypothesized by others. Correlation of the relative sea-level curve for the fringing reef complex (DS3) with a published eustatic curve suggests at least a partial third-order global eustatic control for the highstand part of the sequence. Downstepping DS3 reefs and initial subaerial exposure of earlier DS3 reef strata approximately correlate with initiation of a series of subaerial unconformities in the South Pacific. The longer-term relative fall in sea-level during DS3 downstepping reef progradation does not correlate with a published third-order eustatic fall. Eustatic sea-level fluctuations may have been associated with initiation of the Mediterranean Messinian salinity crisis, but the longer-term fall may have been linked to tectonic uplift in the Mediterranean region. Widespread distribution of 'TCC-style' cycles of approximately the same age suggests a regional (Western Mediterranean) or global control on sea-level change responsible for TCC cycles. In addition, four subaerial exposure-capped TCC cycles may correlate with similar subaerial unconformities in the South Pacific, suggesting at least a partial eustatic control on TCC cyclicity. The high rates of relative sea-level change needed to generate a minimum of 25-30 m sea-level changes associated with each cycle are consistent with glacio-eustacy along with rapid evaporitic drawdown in the Mediterranean. ?? 2001 Elsevier Science B.V. All rights reserved.

Burdigalian turbid water patch reef environment revealed by larger benthic foraminifera

NASA Astrophysics Data System (ADS)

Novak, V.; Renema, W.; Throughflow-project

2012-04-01

Ancient isolated patch reefs outcropping from siliciclastic sediments are a trademark for the Miocene carbonate deposits occurring in East Kalimantan, Indonesia. They develop in transitional shelf sediments deposited between deltaic and deep marine deposits (Allen and Chambers, 1998). The Batu Putih Limestone (Wilson, 2005) and similar outcrops in adjacent areas have been characterized as shallow water carbonates influenced by high siliciclastic input, showing low relief patch reefs in turbid waters. Larger benthic foraminifera (LBF) are excellent markers for biochronology and paleoenvironmental reconstruction. This study aims to reveal age and paleoenvironment of a shallow water carbonate patch reef developed in mixed depositional system by using LBF and microfacies analysis. The studied section is located near Bontang, East Kalimantan, and is approximately 80 m long and 12 m high. It is placed within Miocene sediments in the central part of the Kutai Basin. Patch reef and capping sediments were logged through eight transects along section and divided into nine different lithological units from which samples were collected. Thin sections and isolated specimens of larger benthic foraminifera were analyzed and recognized to species level (where possible) providing age and environmental information. Microfacies analysis of thin sections included carbonate classification (textural scheme of Dunham, 1962) and assemblage composition of LBF, algae and corals relative abundance. Three environmentally indicative groups of LBF were separated based on test morphology, habitat or living relatives (Hallock and Glenn, 1986). Analysed foraminifera assemblage suggests Burdigalian age (Tf1). With use of microfacies analysis nine successive lithological units were grouped into five facies types. Paleoenvironmental reconstruction of LBF fossil assemblage indicate two cycles of possible deepening recorded in the section. Based on high muddy matrix ratio in analyzed thin-sections we still cannot conclude whether they were deeper water assemblage, or that they occurred in shallower water and influenced by turbid conditions as the result of terrigenous input. According to preliminary analysis and siliciclastic content in the sediments the later one should be more likely. Further work will include additional fossil groups analysis (corals, algae and bryozoans), detailed petrographical analysis and Strontium isotope stratigraphy. Allen, G.P., and Chambers, J.L.C. (1998): Sedimentation in the Modern and Miocene Mahakam Delta. Indonesian Petroleum Association, Jakarta, Indonesia, 236 p. Dunham, R.J. (1962): Classification of carbonate rocks according to their depositional texture. In: Ham, W.E., ed., Classification of Carbonate Rocks: American Association of Petroleum Geologists Memoir, v. 1, p. 108-121. Hallock, P. and Glenn, C.E. (1986): Larger Foraminifera: A tool for paleoenvironmental analysis of Cenozoic carbonate depositional facies. Palaios 1, 55-64. Wilson, M.E.J. (2005): Development of equatorial delta-front patch reefs during the Neogene, Borneo. - Journal of Sedimentary Research, 75(1): 114-133.

Tectonic structure and petroleum potential of TayabasBay southeast Luzon, Philippines

NASA Astrophysics Data System (ADS)

Bacud, Jaime; Moore, Aidan; Lee, Chao-Skiing

Tayabas Bay is one of four offshore Philippine areas where the Australian GeologicalSurvey Organization and the Philippine Department of Energy conducted a cooperative marine seismic, gravity, magnetic, bathymetry and geochemical survey. The project acquired new seismic data and reprocessed the 1983 World Bank seismic sections which were all integrated with previous oil company data. the absence of wells drilled offshore, interpretation of offshore seismic data was complemented by onshore well log information and stratigraphy of the Bondoc Peninsula. Geochemistry data, both offshore and onshore, were analyzed to confirm the presence of mature source rocks and hydrocarbon migration. A new seismic interpretation has revealed the structure of this tectonically active geologically complex area. A major structural feature interpreted in offshore Tayabas Bay was a N-NW-trending strike-slip fault which is believed to be a northern splay of the Sibuyan Sea Fault. The authors named this fault the Tayabas Bay Fault and due to its association with the Philippine Fault System the movement is assumed to be left-lateral. The present study suggested the presence of a prolific source rock in the Middle Miocene Vigo Formation and/or the Late Oligocene to Early Miocene Panaon Limestone. Oil and gas generation have been and are occurring in the Bondoc Sub-basin. Two groups of reservoirs were identified, the shelf carbonates beneath the Middle Miocene shales on the Marinduque Platform and the early Middle Miocene carbonates and basin-floor clastics near the base of the Vigo Formation. Carbonate reservoirs are believed to be present in traps formed when the Late Oligocene to Early Miocene carbonate reefs and shelf deposits of the Panaon Limestone were buried by the Middle Miocene shales. A later set of traps was formed and possibly superimposed by the intense deformation associated with the Philippine Fault System which has continued from the Late Pliocene up to the present. Evaluation for hydrocarbon reserves of several possible traps identified three significant leads, namely the Yuni Lead in the south, the Mulanay in the central area and the Mabio in the North.

Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca) of the Western and Central Paratethys.

PubMed

Hyžný, Matúš

2016-10-01

Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19 th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global) extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic "Schlier"-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution during the Oligo-Miocene among the basins in the Paratethys. Based on the co-occurrence of certain decapod species, migration between the Paratethys and the North Sea during the Early Miocene probably occurred via the Rhine Graben. At larger spatial scales, our results suggest that the circum-Mediterranean marine decapod taxa migrated in an easterly direction during the Oligocene and/or Miocene, establishing present-day decapod communities in the Indo-West Pacific.

Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca) of the Western and Central Paratethys

PubMed Central

Hyžný, Matúš

2017-01-01

Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global) extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic “Schlier”-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution during the Oligo-Miocene among the basins in the Paratethys. Based on the co-occurrence of certain decapod species, migration between the Paratethys and the North Sea during the Early Miocene probably occurred via the Rhine Graben. At larger spatial scales, our results suggest that the circum-Mediterranean marine decapod taxa migrated in an easterly direction during the Oligocene and/or Miocene, establishing present-day decapod communities in the Indo-West Pacific. PMID:28239259

Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca) of the Western and Central Paratethys

NASA Astrophysics Data System (ADS)

Hyžný, Matúš

2016-10-01

Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global) extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic "Schlier"-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution during the Oligo-Miocene among the basins in the Paratethys. Based on the co-occurrence of certain decapod species, migration between the Paratethys and the North Sea during the Early Miocene probably occurred via the Rhine Graben. At larger spatial scales, our results suggest that the circum-Mediterranean marine decapod taxa migrated in an easterly direction during the Oligocene and/or Miocene, establishing present-day decapod communities in the Indo-West Pacific.

Subaerially exposed Holocene coral reef, Enriquillo Valley, Dominican Republic

NASA Technical Reports Server (NTRS)

Mann, P.; Taylor, F. W.; Burke, K.; Kulstad, R.

1984-01-01

An extremely well-preserved Holocene fringing coral reef occurs at an average elevation of 5 m below sea level around the margins of the central Enriquillo Valley, Dominican Republic. The reef records the latest marine incursion from the east into an 85-km-long, 12-km-wide tectonic depression and appears to represent a unique preservation. Excellent cross sections of the reef exposed in erosional gullies reveal a composition and zonation typical of modern Caribbean reefs that are found in offshore low-energy environments. Radiocarbon age determinations (2) indicate that reef growth coincided with sea-level rise following the last ice age (5,930 + or - 100 to 4,760 + or - 90 yr B.P.). Deltaic deposition and possible vertical movements on active fault scarps dammed the eastern mouth of the valley and created Lago Enriquillo, the level of which was then rapidly lowered by evaporation in an arid climate to produce a saline lake approximately 40 m below sea level. Stratigraphic studies of rocks along the valley edge and data from drill holes in the basin center indicate that there were earlier post-Miocene marine incursions similar to that described here.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saller, A.H.; Schlanger, S.O.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1000 m of upper Eocene, Oligocene, and lower Miocene carbonates. Strontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids( ), and minormore » planktonic forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic) are abundant in fore-reef, reef, and some back-reef strata. Petrographic and geochemical data indicate aragonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates. Most dolomitization occurred at burial depths of more than 1000 m in cool marine waters circulating through the atoll. lagoonal strata are not significantly altered by marine diagenesis and still contain abundant primary aragonite and magnesium calcite.« less

The evolution of fishes and corals on reefs: form, function and interdependence.

PubMed

Bellwood, David R; Goatley, Christopher H R; Bellwood, Orpha

2017-05-01

Coral reefs are renowned for their spectacular biodiversity and the close links between fishes and corals. Despite extensive fossil records and common biogeographic histories, the evolution of these two key groups has rarely been considered together. We therefore examine recent advances in molecular phylogenetics and palaeoecology, and place the evolution of fishes and corals in a functional context. In critically reviewing the available fossil and phylogenetic evidence, we reveal a marked congruence in the evolution of the two groups. Despite one group consisting of swimming vertebrates and the other colonial symbiotic invertebrates, fishes and corals have remarkably similar evolutionary histories. In the Paleocene and Eocene [66-34 million years ago (Ma)] most modern fish and coral families were present, and both were represented by a wide range of functional morphotypes. However, there is little evidence of diversification at this time. By contrast, in the Oligocene and Miocene (34-5.3 Ma), both groups exhibited rapid lineage diversification. There is also evidence of increasing reef area, occupation of new habitats, increasing coral cover, and potentially, increasing fish abundance. Functionally, the Oligocene-Miocene is marked by the appearance of new fish and coral taxa associated with high-turnover fast-growth ecosystems and the colonization of reef flats. It is in this period that the functional characteristics of modern coral reefs were established. Most species, however, only arose in the last 5.3 million years (Myr; Plio-Pleistocene), with the average age of fish species being 5.3 Myr, and corals just 1.9 Myr. While these species are genetically distinct, phenotypic differences are often limited to variation in colour or minor morphological features. This suggests that the rapid increase in biodiversity during the last 5.3 Myr was not matched by changes in ecosystem function. For reef fishes, colour appears to be central to recent diversification. However, the presence of pigment patterns in the Eocene suggests that colour may not have driven recent diversification. Furthermore, the lack of functional changes in fishes or corals over the last 5 Myr raises questions over the role and importance of biodiversity in shaping the future of coral reefs. © 2016 Cambridge Philosophical Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurst, J.M.; Lapointe, P.A.; Nyein, U.K.

Three Oligocene-Miocene carbonate depositional morphologies commonly occur: shoals, reefs, and isolated platforms. Lenticular shoals (0-25 m thick, 1 km long) are stacked and intercalated with siliciclastic mudstones. Facies include trough/festoon cross-bedded benthic foram grainstones passing laterally and vertically into red-algal dominated graded-laminated beds, bioturbated silty calcareous mudstone, and siliciclastic sandy foram wackestone and packstone. The morphology and facies are hydrodynamically controlled. Pinnacle reefs (1-2 km[sup 2]) dominated by red-algae, branching corals, and large mollusks occur on structure or aligned within shelf mudstones. The latter location reflects low sedimentation rates and hydrodynamic control. Isolated platforms (up to 150 km[sup 2]) aremore » environmental mosaics of marginal path reefs and shoals, interior lagoons, and islands plus marginal slopes. Facies are similar to shoals and reefs except there are more muddy fabrics and less high-energy facies. They develop on tilted fault blocks or eroded submerged arcs in the offshore Gulf of Martaban, distal to the ancestral Irrawaddy delta.« less

Instability and breakdown of the coral-algae symbiosis upon exceedence of the interglacial pCO2 threshold (>260 ppmv): the "missing" Earth-System feedback mechanism

NASA Astrophysics Data System (ADS)

Wooldridge, Scott A.

2017-12-01

Changes in the atmospheric partial pressure of CO2 ( pCO2) leads to predictable impacts on the surface ocean carbonate system. Here, the importance of atmospheric pCO2 <260 ppmv is established for the optimum performance (and stability) of the algal endosymbiosis employed by a key suite of tropical reef-building coral species. Violation of this symbiotic threshold is revealed as a prerequisite for major historical reef extinction events, glacial-interglacial feedback climate cycles, and the modern decline of coral reef ecosystems. Indeed, it is concluded that this symbiotic threshold enacts a fundamental feedback mechanism needed to explain the characteristic dynamics (and drivers) of the coupled land-ocean-atmosphere carbon cycle of the Earth System since the mid-Miocene, some 25 million yr ago.

Cenozoic sea level and the rise of modern rimmed atolls

USGS Publications Warehouse

Toomey, Michael; Ashton, Andrew; Raymo, Maureen E.; Perron, J. Taylor

2016-01-01

Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sea level over the past 8.5 million years. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~ 20 m/Myr) and our numerical modeling results suggest that low sea levels (50–125 m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sea level was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.

Assessment of Differential Uplift Along South Java, Indonesia from Terrace Elevations Mapped with Structure from Motion Photogrammetry

NASA Astrophysics Data System (ADS)

Andreini, J.; Bunds, M. P.; Harris, R. A.; Yulianto, E.; Horns, D. M.; Prasetyadi, C.; Putra, P. S.

2016-12-01

Assessment of Differential Uplift Along South Java, Indonesia from Terrace Elevations Mapped with Structure from Motion Photogrammetry Jeremy Andreini, Michael Bunds, Ronald Harris, Eko Yulianto, Carolus Prasetyadi, Daniel Horns, Purna Putra Is differential uplift occurring on the south coast of Java? Java is on the southern edge of the Sunda plate, above the subducting Indo-Australian plate. Its south coast is 300 km north of the Java Trench and south of the volcanic arc that runs the length of Java. We are investigating relations between marine terraces and convergence, normal faulting associated with tectonically induced basin subsidence, eustatic sea level change, and variations in sediment supply from volcanic activity. Exposed bedrock along the coast includes upper Miocene basinal limestone, and localized exposure of underlying Miocene reef deposits and Oligo-miocene volcanic basement. Differential uplift in the past is implied by north-south trending horst-like ridges of Miocene reef sediment and volcanic basement that have been exhumed from greater depth than adjacent upper Miocene strata. We utilized Quaternary terrace elevations at four locations (Pangamalang, Pangandaran, Karanghawu, and Pacitan). Elevations were measured using traverses with handheld GPS units, profiles made with RTK GPS, and digital surface models (DSMs).The DSMs have 5 cm pixels and were constructed using structure-from-motion (SfM) software to process photos collected with quadcopters equipped with a 24 Mpixel Sony A5100 camera; their vertical RMS error relative to checkpoints measured on bare ground is 6 cm. SfM processing was done in the field with a specially built portable workstation. Four sets of terraces (T) with the following elevations were identified: T1 0-.5 m, T2 2 m, T3 17 m, T4 22 m. We interpret T1 to be the modern wave-cut platform, T2 to represent Holocene uplift of a Holocene terrace or possibly modern deposition, T3 to result from Marine Isotope Stage 5e. T4 occurs at every location except Pangamalang at the western tip of south Java. These results suggest late Quaternary uplift, and the 17 m elevation of T3 indicates an uplift rate of 0.17 mm/yr.

Coral identity underpins architectural complexity on Caribbean reefs.

PubMed

Alvarez-Filip, Lorenzo; Dulvy, Nicholas K; Côte, Isabelle M; Watkinson, Andrew R; Gill, Jennifer A

2011-09-01

The architectural complexity of ecosystems can greatly influence their capacity to support biodiversity and deliver ecosystem services. Understanding the components underlying this complexity can aid the development of effective strategies for ecosystem conservation. Caribbean coral reefs support and protect millions of livelihoods, but recent anthropogenic change is shifting communities toward reefs dominated by stress-resistant coral species, which are often less architecturally complex. With the regionwide decline in reef fish abundance, it is becoming increasingly important to understand changes in coral reef community structure and function. We quantify the influence of coral composition, diversity, and morpho-functional traits on the architectural complexity of reefs across 91 sites at Cozumel, Mexico. Although reef architectural complexity increases with coral cover and species richness, it is highest on sites that are low in taxonomic evenness and dominated by morpho-functionally important, reef-building coral genera, particularly Montastraea. Sites with similar coral community composition also tend to occur on reefs with very similar architectural complexity, suggesting that reef structure tends to be determined by the same key species across sites. Our findings provide support for prioritizing and protecting particular reef types, especially those dominated by key reef-building corals, in order to enhance reef complexity.

Testing the effect of habitat structure and complexity on nekton assemblages using experimental oyster reefs

USGS Publications Warehouse

Humphries, Austin T.; LaPeyre, Megan K.; Kimball, Matthew E.; Rozas, Lawrence P.

2011-01-01

Structurally complex habitats are often associated with more diverse and abundant species assemblages in both aquatic and terrestrial ecosystems. Biogenic reefs formed by the eastern oyster (Crassostrea virginica) are complex in nature and are recognized for their potential habitat value in estuarine systems along the US Atlantic and Gulf of Mexico coasts. Few studies, however, have examined the response of nekton to structural complexity within oyster reefs. We used a quantitative sampling technique to examine how the presence and complexity of experimental oyster reefs influence the abundance, biomass, and distribution of nekton by sampling reefs 4 months and 16 months post-construction. Experimental oyster reefs were colonized immediately by resident fishes and decapod crustaceans, and reefs supported a distinct nekton assemblage compared to mud-bottom habitat. Neither increased reef complexity, nor age of the experimental reef resulted in further changes in nekton assemblages or increases in nekton abundance or diversity. The presence of oyster reefs per se was the most important factor determining nekton usage.

Geology of the d'Entrecasteaux-New Hebrides arc collision zone: results from a deep submersible survey

USGS Publications Warehouse

Collot, J.-Y.; Lallemand, S.; Pelletier, B.; Bissen, J.-P.; Glacon, G.; Fisher, M.A.; Greene, H. Gary; Boulin, J.; Daniel, J.; Monzier, M.

1992-01-01

During the SUBPSO1 cruise, seven submersible dives were conducted between water depths of 5350 and 900 m over the collision zone between the New Hebrides island arc and the d'Entrecasteaux Zone (DEZ). The DEZ, a topographic high on the Australian plate, encompasses the North d'Entrecasteaux Ridge (NDR) and the Bougainville guyot, both of which collide with the island-are slope. In this report we use diving observations and samples, as well as dredging results, to analyse the geology of the Bougainville guyot and the outer arc slope in the DEZ-arc collision zone, and to decipher the mechanisms of scamount subduction. These data indicate that the Bougainville guyot is a middle Eocene island arc volcano capped with reef limestones that appear to have been deposited during the Late Oligocene to Early Miocene and in Miocene-Pliocene times. This guyot possibly emerged during the Middle and Late Miocene, and started to sink in the New Hebrides trench after the Pliocene. The rocks of the New Hebrides arc slope, in the collision zone, consist primarily of Pliocene-Recent volcaniclastic rocks derived from the arc, and underlying fractured island-arc volcanic basement, possibly of Late Miocene age. However, highly sheared, Upper Oligocene to Lower Miocene nannofossil ooze and chalk are exposed at the toe of the arc slope against the northern flank of the NDR. Based on a comparison with cores collected at DSDP Site 286, the ooze and chalk can be interpreted as sediments accreted from the downgoing plate. East of the Bougainville guyot an antiform that developed in the arc slope as a consequence of the collision reveals a 500-m-thick wedge of strongly tectonized rocks, possibly accreted from the guyot or an already subducted seamount. The wedge that is overlain by less deformed volcaniclastic island-arc rocks and sediments includes imbricated layers of Late Oligocene to Early Miocene reef and micritic limestones. This wedge, which develops against the leading flank of the guyot, tends to smooth its high-drag shape. A comparison between the 500-m-thick wedge of limestones that outcrops southeast of the guyot and the absence of such a wedge over the flat top of the guyot, although the top is overthrust by island-arc rocks and sediments, can be interpreted to suggest that the wedge moves in the subduction zone with the guyot and facilitates its subduction by streamlining. ?? 1992.

Relationships between structural complexity, coral traits, and reef fish assemblages

NASA Astrophysics Data System (ADS)

Darling, Emily S.; Graham, Nicholas A. J.; Januchowski-Hartley, Fraser A.; Nash, Kirsty L.; Pratchett, Morgan S.; Wilson, Shaun K.

2017-06-01

With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia's Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals—with different traits and life histories—continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.

Repeated loss of coloniality and symbiosis in scleractinian corals

PubMed Central

Barbeitos, Marcos S.; Romano, Sandra L.; Lasker, Howard R.

2010-01-01

The combination of coloniality and symbiosis in Scleractinia is thought to confer competitive advantage over other benthic invertebrates, and it is likely the key factor for the dominance of corals in tropical reefs. However, the extant Scleractinia are evenly split between zooxanthellate and azooxanthellate species. Most azooxanthellate species are solitary and nearly absent from reefs, but have much wider geographic and bathymetric distributions than reef corals. Molecular phylogenetic analyses have repeatedly recovered clades formed by colonial/zooxanthellate and solitary/azooxanthellate taxa, suggesting that coloniality and symbiosis were repeatedly acquired and/or lost throughout the history of the Scleractinia. Using Bayesian ancestral state reconstruction, we found that symbiosis was lost at least three times and coloniality lost at least six times, and at least two instances in which both characters were lost. All of the azooxanthellate lineages originated from ancestors that were reconstructed as symbiotic, corroborating the onshore–offshore diversification trend recorded in marine taxa. Symbiotic sister taxa of two of these descendant lineages are extant in Caribbean reefs but disappeared from the Mediterranean before the end of the Miocene, whereas extant azooxanthellate lineages have trans-Atlantic distributions. Thus, the phyletic link between reef and nonreef communities may have played an important role in the dynamics of extinction and recovery that marks the evolutionary history of scleractinians, and some reef lineages may have escaped local extinction by diversifying into offshore environments. However, this macroevolutionary mechanism offers no hope of mitigating the effects of climate change on coral reefs in the next century. PMID:20547851

Repeated invasions into the twilight zone: evolutionary origins of a novel assemblage of fishes from deep Caribbean reefs.

PubMed

Tornabene, Luke; Van Tassell, James L; Robertson, D Ross; Baldwin, Carole C

2016-08-01

Mesophotic and deeper reefs of the tropics are poorly known and underexplored ecosystems worldwide. Collectively referred to as the 'twilight zone', depths below ~30-50 m are home to many species of reef fishes that are absent from shallower depths, including many undescribed and endemic species. We currently lack even a basic understanding of the diversity and evolutionary origins of fishes on tropical mesophotic reefs. Recent submersible collections in the Caribbean have provided new specimens that are enabling phylogenetic reconstructions that incorporate deep-reef representatives of tropical fish genera. Here, we investigate evolutionary depth transitions in the family Gobiidae (gobies), the most diverse group of tropical marine fishes. Using divergence-time estimation coupled with stochastic character mapping to infer the timing of shallow-to-deep habitat transitions in gobies, we demonstrate at least four transitions from shallow to mesophotic depths. Habitat transitions occurred in two broad time periods (Miocene, Pliocene-Pleistocene), and may have been linked to the availability of underutilized niches, as well as the evolution of morphological/behavioural adaptations for life on deep reefs. Further, our analysis shows that at least three evolutionary lineages that invaded deep habitats subsequently underwent speciation, reflecting another unique mode of radiation within the Gobiidae. Lastly, we synthesize depth distributions for 95 species of Caribbean gobies, which reveal major bathymetric faunal breaks at the boundary between euphotic and mesophotic reefs. Ultimately, our study is the first rigorous investigation into the origin of Caribbean deep-reef fishes and provides a framework for future studies that utilize rare, deep-reef specimens. © 2016 John Wiley & Sons Ltd.

Flattening of Caribbean coral reefs: region-wide declines in architectural complexity

PubMed Central

Alvarez-Filip, Lorenzo; Dulvy, Nicholas K.; Gill, Jennifer A.; Côté, Isabelle M.; Watkinson, Andrew R.

2009-01-01

Coral reefs are rich in biodiversity, in large part because their highly complex architecture provides shelter and resources for a wide range of organisms. Recent rapid declines in hard coral cover have occurred across the Caribbean region, but the concomitant consequences for reef architecture have not been quantified on a large scale to date. We provide, to our knowledge, the first region-wide analysis of changes in reef architectural complexity, using nearly 500 surveys across 200 reefs, between 1969 and 2008. The architectural complexity of Caribbean reefs has declined nonlinearly with the near disappearance of the most complex reefs over the last 40 years. The flattening of Caribbean reefs was apparent by the early 1980s, followed by a period of stasis between 1985 and 1998 and then a resumption of the decline in complexity to the present. Rates of loss are similar on shallow (<6 m), mid-water (6–20 m) and deep (>20 m) reefs and are consistent across all five subregions. The temporal pattern of declining architecture coincides with key events in recent Caribbean ecological history: the loss of structurally complex Acropora corals, the mass mortality of the grazing urchin Diadema antillarum and the 1998 El Nino Southern Oscillation-induced worldwide coral bleaching event. The consistently low estimates of current architectural complexity suggest regional-scale degradation and homogenization of reef structure. The widespread loss of architectural complexity is likely to have serious consequences for reef biodiversity, ecosystem functioning and associated environmental services. PMID:19515663

Retention of Habitat Complexity Minimizes Disassembly of Reef Fish Communities following Disturbance: A Large-Scale Natural Experiment

PubMed Central

Emslie, Michael J.; Cheal, Alistair J.; Johns, Kerryn A.

2014-01-01

High biodiversity ecosystems are commonly associated with complex habitats. Coral reefs are highly diverse ecosystems, but are under increasing pressure from numerous stressors, many of which reduce live coral cover and habitat complexity with concomitant effects on other organisms such as reef fishes. While previous studies have highlighted the importance of habitat complexity in structuring reef fish communities, they employed gradient or meta-analyses which lacked a controlled experimental design over broad spatial scales to explicitly separate the influence of live coral cover from overall habitat complexity. Here a natural experiment using a long term (20 year), spatially extensive (∼115,000 kms2) dataset from the Great Barrier Reef revealed the fundamental importance of overall habitat complexity for reef fishes. Reductions of both live coral cover and habitat complexity had substantial impacts on fish communities compared to relatively minor impacts after major reductions in coral cover but not habitat complexity. Where habitat complexity was substantially reduced, species abundances broadly declined and a far greater number of fish species were locally extirpated, including economically important fishes. This resulted in decreased species richness and a loss of diversity within functional groups. Our results suggest that the retention of habitat complexity following disturbances can ameliorate the impacts of coral declines on reef fishes, so preserving their capacity to perform important functional roles essential to reef resilience. These results add to a growing body of evidence about the importance of habitat complexity for reef fishes, and represent the first large-scale examination of this question on the Great Barrier Reef. PMID:25140801

Retention of habitat complexity minimizes disassembly of reef fish communities following disturbance: a large-scale natural experiment.

PubMed

Emslie, Michael J; Cheal, Alistair J; Johns, Kerryn A

2014-01-01

High biodiversity ecosystems are commonly associated with complex habitats. Coral reefs are highly diverse ecosystems, but are under increasing pressure from numerous stressors, many of which reduce live coral cover and habitat complexity with concomitant effects on other organisms such as reef fishes. While previous studies have highlighted the importance of habitat complexity in structuring reef fish communities, they employed gradient or meta-analyses which lacked a controlled experimental design over broad spatial scales to explicitly separate the influence of live coral cover from overall habitat complexity. Here a natural experiment using a long term (20 year), spatially extensive (∼ 115,000 kms(2)) dataset from the Great Barrier Reef revealed the fundamental importance of overall habitat complexity for reef fishes. Reductions of both live coral cover and habitat complexity had substantial impacts on fish communities compared to relatively minor impacts after major reductions in coral cover but not habitat complexity. Where habitat complexity was substantially reduced, species abundances broadly declined and a far greater number of fish species were locally extirpated, including economically important fishes. This resulted in decreased species richness and a loss of diversity within functional groups. Our results suggest that the retention of habitat complexity following disturbances can ameliorate the impacts of coral declines on reef fishes, so preserving their capacity to perform important functional roles essential to reef resilience. These results add to a growing body of evidence about the importance of habitat complexity for reef fishes, and represent the first large-scale examination of this question on the Great Barrier Reef.

Geomorphology of unique reefs on the western Canadian shelf: sponge reefs mapped by multibeam bathymetry

NASA Astrophysics Data System (ADS)

Conway, Kim W.; Barrie, J. Vaughn; Krautter, Manfred

2005-09-01

Multibeam imagery of siliceous sponge reefs (Hexactinellida, Hexactinosida) reveals the setting, form, and organization of five reef complexes on the western Canadian continental shelf. The reefs are built by framework skeleton sponges which trap clay-rich sediments resulting in a distinctive pattern of low intensity backscatter from the reefs that colonize more reflective glacial sediments of higher backscatter intensity. Bathymetry and backscatter maps show the distribution and form of reefs in two large complexes in the Queen Charlotte Basin (QCB) covering hundreds of km2, and three smaller reef complexes in the Georgia Basin (GB). Ridges up to 7 km long and 21 m in height, together with diversely shaped, coalescing bioherms and biostromes form the principal reef shape in the QCB whereas chains of wave-form, streamlined mounds up to 14 m in height have developed in the GB. Reef initiation is dependent on the distribution of high backscatter-intensity relict glacial surfaces, and the variation in reef complex morphology is probably the result of tidally driven, near seabed currents.

Revised Stratigraphy of The Nallıhan-Dudaş (Beypazarı) Area and Significance of the Campanian-Maastrichtian Reef Occurrences Based on the Foraminiferal and Rudist Data

NASA Astrophysics Data System (ADS)

Görmüş, Muhittin; Sami Us, Muhammed; Özer, Sacit; Tekin, Erdoǧan; Akpınar, Serap; Kabakcı, Büşra

2016-04-01

Transgressive to regressive succession of the Cretaceous Period and Cretaceous Paleogene boundary from the Nallıhan-Beypazarı area have significant data to interpret the past geological history of northwestern Turkey. In the literature, main scientific differences are seen on the formation/lithodem names, their ages, contact relations and environmental interpretations. In the study, a revision has been made for a proper stratigraphy of the area. For the revised stratigraphy, the obtained results from our field and laboratory works and the literature information were used. The following stratigraphy were established from basement to top: the Permo-Triassic aged Sekli metamorphics, Jurassic to lower Cretaceous Soǧukçam formation, Campanian to Maastrichtian aged Dereköy Group-Haremiköy conglomerates, Çeǧiköy reefs, Nardin formation (Seben formation), Taraklı formation; the Paleogene aged Kızılçay group including Kızılbayır formation, Karaköy volcanoclastics, Selvipınar limestone, the Miocene-Pliocene terrestrial sediments, Çoraklar formation, Hırka formation, Akpınar formation, Çayırhan formation, Teke volkanics, Bozbelen formation, Kirmir formation. The main unconformities are between Jura and Campanian, Maastrichtian and Paleogene, Eocene and Miocene times. Among the geological units, the Çeǧiköy reefs having rich rudist fauna overlie the Haremiköy conglomerates in both sides at the north-Yeşilyurt village and at the south-Gökçeöz village. Another outcrop, Emincik is between two mentioned villages. Biohermal reefs mainly includes very rich rudists up to 40 centimetres in size around the Yeşilköy such as: Pironaea polystyla, Vaccinites loftusi, Hippurites sublaevis. Larger foraminifera Orbitoides medius, O. apiculatus, Siderolites calcitrapoides, Pseodosiderolites vidali are also common in the fore reef areas. Around the Gökçeöz at the south part, the identified rudists are as follows: Vaccinites sp., Hippurites aff. sublaevis, Pironaea polystyla Joufia cf. reticulata, Hippuritella variabilis. In this location, smaller rudists are at the bottom, larger ones are at the top of the biostromal limestones. The first reefal occurrences are interpreted as local fringing type reefs. The reefs around the Emincik are the second occurrences of reefs. This was interpreted as patch reefs. Rudist fauna are less than the other locations and it occurs above the orbitoid rich siliciclastics. Extinction of rudists is at the end of middle Maastrichtian due to paleoenvironmental changes and open marine conditions. Transgressive succession continuous with regressive succession. The Taraklı Formation siliciclastics including rich Orbitoides apiculatus and O. gruenbachensis. The location is also important for the mass larger foraminifera-Orbitoides extinction on the Cretaceous/Paleogene boundary. Terrestrial siliciclastics overlies the very shallow marine Maastrichtian siliciclastics. ACKNOWLADGEMENT: The authors thanks to Ankara University Scientific Research Projects Coordination Unit (BAP) for the financial support on the project 13B4343014.

Does reef architectural complexity influence resource availability for a large reef-dwelling invertebrate?

NASA Astrophysics Data System (ADS)

Lozano-Álvarez, Enrique; Luviano-Aparicio, Nelia; Negrete-Soto, Fernando; Barradas-Ortiz, Cecilia; Aguíñiga-García, Sergio; Morillo-Velarde, Piedad S.; Álvarez-Filip, Lorenzo; Briones-Fourzán, Patricia

2017-10-01

In coral reefs, loss of architectural complexity and its associated habitat degradation is expected to affect reef specialists in particular due to changes in resource availability. We explored whether these features could potentially affect populations of a large invertebrate, the spotted spiny lobster Panulirus guttatus, which is an obligate Caribbean coral reef-dweller with a limited home range. We selected two separate large coral reef patches in Puerto Morelos (Mexico) that differed significantly in structural complexity and level of degradation, as assessed via the rugosity index, habitat assessment score, and percent cover of various benthic components. On each reef, we estimated density of P. guttatus and sampled lobsters to analyze their stomach contents, three different condition indices, and stable isotopes (δ15N and δ13C) in muscle. Lobster density did not vary with reef, suggesting that available crevices in the less complex patch still provided adequate refuge to these lobsters. Lobsters consumed many food types, dominated by mollusks and crustaceans, but proportionally more crustaceans (herbivore crabs) in the less complex patch, which had more calcareous macroalgae and algal turf. Lobsters from both reefs had a similar condition (all three indices) and mean δ15N, suggesting a similar quality of diet between reefs related to their opportunistic feeding, but differed in mean δ13C values, reflecting the different carbon sources between reefs and providing indirect evidence of individuals of P. guttatus foraging exclusively over their home reef. Overall, we found no apparent effects of architectural complexity, at least to the degree observed in our less complex patch, on density, condition, or trophic level of P. guttatus.

Digital Reef Rugosity Estimates Coral Reef Habitat Complexity

PubMed Central

Dustan, Phillip; Doherty, Orla; Pardede, Shinta

2013-01-01

Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity. PMID:23437380

Digital reef rugosity estimates coral reef habitat complexity.

PubMed

Dustan, Phillip; Doherty, Orla; Pardede, Shinta

2013-01-01

Ecological habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity.

Parascolymia (Scleractinia: Lobophylliidae) in the Central Paratethys Sea (Vienna Basin, Austria) and its possible biogeographic implications

PubMed Central

Reuter, Markus; Wiedl, Thomas; Piller, Werner E.

2015-01-01

Palaeobiogeographical and palaeodiversity patterns of scleractinian reef corals are generally biased due to uncertain taxonomy and a loss of taxonomic characters through dissolution and recrystallization of the skeletal aragonite in shallow marine limestones. Herein, we describe a fossil lobophylliid coral in mouldic preservation from the early middle Miocene Leitha Limestone of the Central Paratethys Sea (Vienna Basin, Austria). By using grey-scale image inversion and silicone rubber casts for the visualization of the original skeletal anatomy and the detection of distinct micromorphological characters (i.e. shape of septal teeth, granulation of septocostae) Parascolymia bracherti has been identified as a new species in spite of the dissolved skeleton. In the recent era, Parascolymia like all Lobophylliidae is restricted to the Indo-Pacific region, where it is represented by a single species. The new species proves the genus also in the Miocene Mediterranean reef coral province. A review of the spatio-temporal relationships of fossil corals related to Parascolymia indicates that the genus was probably rooted in the Eastern Atlantic‒Western Tethys region during the Paleocene to Eocene and reached the Indo-Pacific region not before the Oligocene. The revealed palaeobiogeographical pattern shows an obvious congruence with that of Acropora and tridacnine bivalves reflecting a gradual equatorwards retreat of the marine biodiversity center parallel to the Cenozoic climate deterioration. PMID:26201071

Amplitude of late Miocene sea-level fluctuations from karst development in reef-slope deposits (SE Spain)

NASA Astrophysics Data System (ADS)

Reolid, Jesús; Betzler, Christian; Braga, Juan Carlos

2016-11-01

A prograding late Miocene carbonate platform in southern Spain revealing different sea-level pinning points was analysed with the aim to increase the accuracy of reconstruction of past sea-level changes. These pinning points are distinct diagenetic zones (DZ) and the position of reef-framework deposits. DZ1 is defined by the dissolution of bioclastic components and DZ2 by calcitic cement precipitation in dissolution pores. Calcite cements are granular and radiaxial fibrous, and are of meteoric origin as deduced from cathodoluminescence, EDX spectroscopy, as well as from δ13C and δ18O isotope analyses. DZ3 has moldic porosity after aragonitic bioclasts with minor granular calcitic cements. DZ1 and DZ2 indicate karstification and the development of a coastal palaeoaquifer during a sea-level lowstand. DZ3 diagenetic features are related to the final subaerial exposure of the section during the Messinian Salinity Crisis. Facies and diagenetic data reveal a complete cycle of sea-level fall (23 ± 1 m) and rise (31 ± 1 m). A robust age model based on magneto- and cyclostratigraphy for these deposits places this cycle between 5.89 and 5.87 Ma. Therefore, for the first time, this work allows a direct comparison of an outcrop with a pelagic marine proxy record of a specific Neogene sea-level fluctuation.

A multiscale analysis of coral reef topographic complexity using lidar-derived bathymetry

USGS Publications Warehouse

Zawada, D.G.; Brock, J.C.

2009-01-01

Coral reefs represent one of the most irregular substrates in the marine environment. This roughness or topographic complexity is an important structural characteristic of reef habitats that affects a number of ecological and environmental attributes, including species diversity and water circulation. Little is known about the range of topographic complexity exhibited within a reef or between different reef systems. The objective of this study was to quantify topographic complexity for a 5-km x 5-km reefscape along the northern Florida Keys reef tract, over spatial scales ranging from meters to hundreds of meters. The underlying dataset was a 1-m spatial resolution, digital elevation model constructed from lidar measurements. Topographic complexity was quantified using a fractal algorithm, which provided a multi-scale characterization of reef roughness. The computed fractal dimensions (D) are a measure of substrate irregularity and are bounded between values of 2 and 3. Spatial patterns in D were positively correlated with known reef zonation in the area. Landward regions of the study site contain relatively smooth (D ??? 2.35) flat-topped patch reefs, which give way to rougher (D ??? 2.5), deep, knoll-shaped patch reefs. The seaward boundary contains a mixture of substrate features, including discontinuous shelf-edge reefs, and exhibits a corresponding range of roughness values (2.28 ??? D ??? 2.61). ?? 2009 Coastal Education and Research Foundation.

Flat and complex temperate reefs provide similar support for fish: Evidence for a unimodal species-habitat relationship.

PubMed

Paxton, Avery B; Pickering, Emily A; Adler, Alyssa M; Taylor, J Christopher; Peterson, Charles H

2017-01-01

Structural complexity, a form of habitat heterogeneity, influences the structure and function of ecological communities, generally supporting increased species density, richness, and diversity. Recent research, however, suggests the most complex habitats may not harbor the highest density of individuals and number of species, especially in areas with elevated human influence. Understanding nuances in relationships between habitat heterogeneity and ecological communities is warranted to guide habitat-focused conservation and management efforts. We conducted fish and structural habitat surveys of thirty warm-temperate reefs on the southeastern US continental shelf to quantify how structural complexity influences fish communities. We found that intermediate complexity maximizes fish abundance on natural and artificial reefs, as well as species richness on natural reefs, challenging the current paradigm that abundance and other fish community metrics increase with increasing complexity. Naturally occurring rocky reefs of flat and complex morphologies supported equivalent abundance, biomass, species richness, and community composition of fishes. For flat and complex morphologies of rocky reefs to receive equal consideration as essential fish habitat (EFH), special attention should be given to detecting pavement type rocky reefs because their ephemeral nature makes them difficult to detect with typical seafloor mapping methods. Artificial reefs of intermediate complexity also maximized fish abundance, but human-made structures composed of low-lying concrete and metal ships differed in community types, with less complex, concrete structures supporting lower numbers of fishes classified largely as demersal species and metal ships protruding into the water column harboring higher numbers of fishes, including more pelagic species. Results of this study are essential to the process of evaluating habitat function provided by different types and shapes of reefs on the seafloor so that all EFH across a wide range of habitat complexity may be accurately identified and properly managed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nyagah, K.; Cloeter, J.J.; Maende, A.

The Lamu basin occupies the coastal onshore and offshore areas of south-east Kenya. This fault bounded basin formed as a result of the Paleozoic-early Mesozoic phase of rifting that developed at the onset of Gondwana dismemberment. The resultant graben was filled by Karroo (Permian-Early Jurassic) continental siliciclastic sediments. Carbonate deposits associated with the Tethyan sea invasion, dominate the Middle to Late Jurassic basin fill. Cessation of the relative motion between Madagascar and Africa in the Early Cretaceous, heralded passive margin development and deltaic sediment progradation until the Paleogene. Shallow seas transgressed the basin in the Miocene when another carbonate regimemore » prevailed. The basin depositional history is characterized by pulses of transgressive and regressive cycles, bounded by tectonically enhanced unconformities dividing the total sedimentary succession into discrete megasequences. Source rock strata occur within Megasequence III (Paleogene) depositional cycle and were lowered into the oil window in Miocene time, when the coastal parts of the basin experienced the greatest amount of subsidence. The tectono-eustatic pulses of the Tertiary brought about source and reservoir strata into a spatial relationship in which hydrocarbons could be entrapped. A basement high on the continental shelf has potential for Karroo sandstone and Jurassic limestone reservoirs. Halokinesis of Middle Jurassic salt in Miocene time provides additional prospects in the offshore area. Paleogene deltaic sands occur in rotated listric fault blacks. A Miocene reef Play coincides with an Eocene source rock kitchen.« less

Healthy coral reefs may assure coastal protection in face of climate change related sea level rise

NASA Astrophysics Data System (ADS)

Harris, D. L.; Rovere, A.; Parravicini, V.; Casella, E.; Canavesio, R.; Collin, A.

2016-12-01

Coral reefs are diverse ecosystems that support millions of people worldwide providing crucial services, of which, coastal protection is one of the most relevant. The efficiency of coral reefs in protecting coastlines and dissipating waves is directly linked to the cover of living corals and three dimensional reef structural complexity. Climate change and human impacts are leading to severe global reductions in live coral cover, posing serious concerns regarding the capacity of degraded reef systems in protecting tropical coastal regions. Although it is known that the loss of structurally complex reefs may lead to greater erosion of coastlines, this process has rarely been quantified and it is still unknown whether the maintenance of healthy reefs through conservation will be enough to guarantee coastal protection during rising sea levels. We show that a significant loss of wave dissipation and a subsequent increase in back-reef wave height (up to 5 times present wave height) could occur even at present sea level if living corals are lost and reef structural complexity is reduced. Yet we also show that healthy reefs, measured by structural complexity and efficiency of vertical reef accretion, may maintain their present capacity of wave dissipation even under rising sea levels. Our results indicate that the health of coral reefs and not sea level rise will be the major determinant of the coastal protection services provided by coral reefs and calls for investments into coral reef conservation to ensure the future protection of tropical coastal communities.

Reef flattening effects on total richness and species responses in the Caribbean.

PubMed

Newman, Steven P; Meesters, Erik H; Dryden, Charlie S; Williams, Stacey M; Sanchez, Cristina; Mumby, Peter J; Polunin, Nicholas V C

2015-11-01

There has been ongoing flattening of Caribbean coral reefs with the loss of habitat having severe implications for these systems. Complexity and its structural components are important to fish species richness and community composition, but little is known about its role for other taxa or species-specific responses. This study reveals the importance of reef habitat complexity and structural components to different taxa of macrofauna, total species richness, and individual coral and fish species in the Caribbean. Species presence and richness of different taxa were visually quantified in one hundred 25-m(2) plots in three marine reserves in the Caribbean. Sampling was evenly distributed across five levels of visually estimated reef complexity, with five structural components also recorded: the number of corals, number of large corals, slope angle, maximum sponge and maximum octocoral height. Taking advantage of natural heterogeneity in structural complexity within a particular coral reef habitat (Orbicella reefs) and discrete environmental envelope, thus minimizing other sources of variability, the relative importance of reef complexity and structural components was quantified for different taxa and individual fish and coral species on Caribbean coral reefs using boosted regression trees (BRTs). Boosted regression tree models performed very well when explaining variability in total (82·3%), coral (80·6%) and fish species richness (77·3%), for which the greatest declines in richness occurred below intermediate reef complexity levels. Complexity accounted for very little of the variability in octocorals, sponges, arthropods, annelids or anemones. BRTs revealed species-specific variability and importance for reef complexity and structural components. Coral and fish species occupancy generally declined at low complexity levels, with the exception of two coral species (Pseudodiploria strigosa and Porites divaricata) and four fish species (Halichoeres bivittatus, H. maculipinna, Malacoctenus triangulatus and Stegastes partitus) more common at lower reef complexity levels. A significant interaction between country and reef complexity revealed a non-additive decline in species richness in areas of low complexity and the reserve in Puerto Rico. Flattening of Caribbean coral reefs will result in substantial species losses, with few winners. Individual structural components have considerable value to different species, and their loss may have profound impacts on population responses of coral and fish due to identity effects of key species, which underpin population richness and resilience and may affect essential ecosystem processes and services. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Coral reef structural complexity provides important coastal protection from waves under rising sea levels.

PubMed

Harris, Daniel L; Rovere, Alessio; Casella, Elisa; Power, Hannah; Canavesio, Remy; Collin, Antoine; Pomeroy, Andrew; Webster, Jody M; Parravicini, Valeriano

2018-02-01

Coral reefs are diverse ecosystems that support millions of people worldwide by providing coastal protection from waves. Climate change and human impacts are leading to degraded coral reefs and to rising sea levels, posing concerns for the protection of tropical coastal regions in the near future. We use a wave dissipation model calibrated with empirical wave data to calculate the future increase of back-reef wave height. We show that, in the near future, the structural complexity of coral reefs is more important than sea-level rise in determining the coastal protection provided by coral reefs from average waves. We also show that a significant increase in average wave heights could occur at present sea level if there is sustained degradation of benthic structural complexity. Our results highlight that maintaining the structural complexity of coral reefs is key to ensure coastal protection on tropical coastlines in the future.

Coral reef structural complexity provides important coastal protection from waves under rising sea levels

PubMed Central

Harris, Daniel L.; Rovere, Alessio; Casella, Elisa; Power, Hannah; Canavesio, Remy; Collin, Antoine; Pomeroy, Andrew; Webster, Jody M.; Parravicini, Valeriano

2018-01-01

Coral reefs are diverse ecosystems that support millions of people worldwide by providing coastal protection from waves. Climate change and human impacts are leading to degraded coral reefs and to rising sea levels, posing concerns for the protection of tropical coastal regions in the near future. We use a wave dissipation model calibrated with empirical wave data to calculate the future increase of back-reef wave height. We show that, in the near future, the structural complexity of coral reefs is more important than sea-level rise in determining the coastal protection provided by coral reefs from average waves. We also show that a significant increase in average wave heights could occur at present sea level if there is sustained degradation of benthic structural complexity. Our results highlight that maintaining the structural complexity of coral reefs is key to ensure coastal protection on tropical coastlines in the future. PMID:29503866

Coral reef complexes at an atypical windward platform margin: Late Quaternary, southeast Florida

USGS Publications Warehouse

Lidz, B.H.

2004-01-01

Major coral reef complexes rim many modern and ancient carbonate platforms. Their role in margin evolution is not fully understood, particularly when they border a margin atypical of the classic model. Classic windward margins are steeply inclined. The windward margin of southeast Florida is distinct with a very low-gradient slope and a shelf edge ringed with 30-m-high Quaternary outlier reefs on a shallow upper-slope terrace. A newly developed synthesis of temporally well-constrained geologic events is used with surface and subsurface seismic-reflection contours to construct morphogenetic models of four discontinuous reef-complex sequences. The models show uneven subsurface topography, upward and landward buildups, and a previously unreported, rapid, Holocene progradation. The terms backstepped reef-complex margin, backfilled prograded margin, and coalesced reef-complex margin are proposed for sections exhibiting suitable signatures in the stratigraphic record. The models have significant implications for interpretation of ancient analogues. The Florida record chronicles four kinds of geologic events. (1) Thirteen transgressions high enough for marine deposition occurred between ca. 325 ka and the present. Six gave rise to stratigraphically successive coral reef complexes between ca. 185 and ca. 77.8 ka. The seventh reef ecosystem is Holocene. (2) Two primary coral reef architectures built the outer shelf and margin, producing respective ridge-and-swale and reef-and-trough geometries of very different scales. (3) Massive outlier reefs developed on an upper-slope terrace between ca. 106.5 and ca. 80 ka and are inferred to contain corals that would date to highstands at ca. 140 and 125 ka. (4) Sea level remained below elevation of the shelf between ca. 77.8 and ca. 9.6 ka. ?? 2004 Geological Society of America.

Glowing Seashells: Diversity of Fossilized Coloration Patterns on Coral Reef-Associated Cone Snail (Gastropoda: Conidae) Shells from the Neogene of the Dominican Republic

PubMed Central

Hendricks, Jonathan R.

2015-01-01

The biology of modern Conidae (cone snails)—which includes the hyperdiverse genus Conus—has been intensively studied, but the fossil record of the clade remains poorly understood, particularly within an evolutionary framework. Here, ultraviolet light is used to reveal and characterize the original shell coloration patterns of 28 species of cone snails from three Neogene coral reef-associated deposits from the Cibao Valley, northern Dominican Republic. These fossils come from the upper Miocene Cercado Fm. and lower Pliocene Gurabo Fm., and range in age from about 6.6-4.8 Ma. Comparison of the revealed coloration patterns with those of extant species allow the taxa to be assigned to three genera of cone snails (Profundiconus, Conasprella, and Conus) and at least nine subgenera. Thirteen members of these phylogenetically diverse reef faunas are described as new species. These include: Profundiconus? hennigi, Conasprella (Ximeniconus) ageri, Conus anningae, Conus lyelli, Conus (Atlanticonus?) franklinae, Conus (Stephanoconus) gouldi, Conus (Stephanoconus) bellacoensis, Conus (Ductoconus) cashi, Conus (Dauciconus) garrisoni, Conus (Dauciconus?) zambaensis, Conus (Spuriconus?) kaesleri, Conus (Spuriconus?) lombardii, and Conus (Lautoconus?) carlottae. Each of the three reef deposits contain a minimum of 14–16 cone snail species, levels of diversity that are similar to modern Indo-Pacific reef systems. Finally, most of the 28 species can be assigned to modern clades and thus have important implications for understanding the biogeographic and temporal histories of these clades in tropical America. PMID:25830769

Species-area relationships in coral communities: evaluating mechanisms for a commonly observed pattern

NASA Astrophysics Data System (ADS)

Huntington, B. E.; Lirman, D.

2012-12-01

Landscape-scale attributes of patch size, spatial isolation, and topographic complexity are known to influence diversity and abundance in terrestrial and marine systems, but remain collectively untested for reef-building corals. To investigate the relationship between the coral assemblage and seascape variation in reef habitats, we took advantage of the distinct boundaries, spatial configurations, and topographic complexities among artificial reef patches to overcome the difficulties of manipulating natural reefs. Reef size (m2) was found to be the foremost predictor of coral richness in accordance with species-area relationship predictions. Larger reefs were also found to support significantly higher colony densities, enabling us to reject the null hypothesis of random placement (a sampling artifact) in favor of target area predictions that suggest greater rates of immigration on larger reefs. Unlike the pattern previously documented for reef fishes, topographic complexity was not a significant predictor of any coral assemblage response variable, despite the range of complexity values sampled. Lastly, coral colony density was best explained by both increasing reef size and decreasing reef spatial isolation, a pattern found exclusively among brooding species with shorter larval dispersal distances. We conclude that seascape attributes of reef size and spatial configuration within the seascape can influence the species richness and abundance of the coral community at relatively small spatial scales (<1 km). Specifically, we demonstrate how patterns in the coral communities that have naturally established on these manipulated reefs agree with the target area and island biogeography mechanisms to drive species-area relationships in reef-building corals. Based on the patterns documented in artificial reefs, habitat degradation that results in smaller, more isolated natural reefs may compromise coral diversity.

Flat and complex temperate reefs provide similar support for fish: Evidence for a unimodal species-habitat relationship

PubMed Central

Pickering, Emily A.; Adler, Alyssa M.; Taylor, J. Christopher; Peterson, Charles H.

2017-01-01

Structural complexity, a form of habitat heterogeneity, influences the structure and function of ecological communities, generally supporting increased species density, richness, and diversity. Recent research, however, suggests the most complex habitats may not harbor the highest density of individuals and number of species, especially in areas with elevated human influence. Understanding nuances in relationships between habitat heterogeneity and ecological communities is warranted to guide habitat-focused conservation and management efforts. We conducted fish and structural habitat surveys of thirty warm-temperate reefs on the southeastern US continental shelf to quantify how structural complexity influences fish communities. We found that intermediate complexity maximizes fish abundance on natural and artificial reefs, as well as species richness on natural reefs, challenging the current paradigm that abundance and other fish community metrics increase with increasing complexity. Naturally occurring rocky reefs of flat and complex morphologies supported equivalent abundance, biomass, species richness, and community composition of fishes. For flat and complex morphologies of rocky reefs to receive equal consideration as essential fish habitat (EFH), special attention should be given to detecting pavement type rocky reefs because their ephemeral nature makes them difficult to detect with typical seafloor mapping methods. Artificial reefs of intermediate complexity also maximized fish abundance, but human-made structures composed of low-lying concrete and metal ships differed in community types, with less complex, concrete structures supporting lower numbers of fishes classified largely as demersal species and metal ships protruding into the water column harboring higher numbers of fishes, including more pelagic species. Results of this study are essential to the process of evaluating habitat function provided by different types and shapes of reefs on the seafloor so that all EFH across a wide range of habitat complexity may be accurately identified and properly managed. PMID:28873447

Using airborne laser altimetry to estimate Sabellaria alveolata (Polychaeta: Sabellariidae) reefs volume in tidal flat environments

NASA Astrophysics Data System (ADS)

Noernberg, Mauricio Almeida; Fournier, Jérôme; Dubois, Stanislas; Populus, Jacques

2010-12-01

This study has exploited aerial photographs and LiDAR digital elevation model to quantify intertidal complex landforms volume. A first volume estimation of the main sabellariid polychaete reef complex of the Bay of Mont-Saint-Michel - France is presented. The Sabellaria alveolata is an engineering species that heavily modifies its environment. This gregarious tube-building annelid forms dense and solid reefs of bioclastic coarse sand which can reach several km 2. Since 1970 a very strong decline of reefs has been observed. The authorities have curbed fishing activities without any noticeable changes in reef health status. The S. alveolata reef volume is estimated to be 132 048 m 3 (96 301 m 3 for Sainte-Anne reef and 35 747 m 3 for Champeaux reef). Further LiDAR data surveys will be needed to be able to understand and quantify the accretion/erosion processes in play in the reef dynamic. Because of the internal variability of topographic complexity of the reef, characterized by crevices, cracks, and holes rather than whole blocks, further studies are needed to calculate more accurately the volume of the reef.

Linking social and ecological systems to sustain coral reef fisheries.

PubMed

Cinner, Joshua E; McClanahan, Timothy R; Daw, Tim M; Graham, Nicholas A J; Maina, Joseph; Wilson, Shaun K; Hughes, Terence P

2009-02-10

The ecosystem goods and services provided by coral reefs are critical to the social and economic welfare of hundreds of millions of people, overwhelmingly in developing countries [1]. Widespread reef degradation is severely eroding these goods and services, but the socioeconomic factors shaping the ways that societies use coral reefs are poorly understood [2]. We examine relationships between human population density, a multidimensional index of socioeconomic development, reef complexity, and the condition of coral reef fish populations in five countries across the Indian Ocean. In fished sites, fish biomass was negatively related to human population density, but it was best explained by reef complexity and a U-shaped relationship with socioeconomic development. The biomass of reef fishes was four times lower at locations with intermediate levels of economic development than at locations with both low and high development. In contrast, average biomass inside fishery closures was three times higher than in fished sites and was not associated with socioeconomic development. Sustaining coral reef fisheries requires an integrated approach that uses tools such as protected areas to quickly build reef resources while also building capacities and capital in societies over longer time frames to address the complex underlying causes of reef degradation.

The dynamics of architectural complexity on coral reefs under climate change.

PubMed

Bozec, Yves-Marie; Alvarez-Filip, Lorenzo; Mumby, Peter J

2015-01-01

One striking feature of coral reef ecosystems is the complex benthic architecture which supports diverse and abundant fauna, particularly of reef fish. Reef-building corals are in decline worldwide, with a corresponding loss of live coral cover resulting in a loss of architectural complexity. Understanding the dynamics of the reef architecture is therefore important to envision the ability of corals to maintain functional habitats in an era of climate change. Here, we develop a mechanistic model of reef topographical complexity for contemporary Caribbean reefs. The model describes the dynamics of corals and other benthic taxa under climate-driven disturbances (hurricanes and coral bleaching). Corals have a simplified shape with explicit diameter and height, allowing species-specific calculation of their colony surface and volume. Growth and the mechanical (hurricanes) and biological erosion (parrotfish) of carbonate skeletons are important in driving the pace of extension/reduction in the upper reef surface, the net outcome being quantified by a simple surface roughness index (reef rugosity). The model accurately simulated the decadal changes of coral cover observed in Cozumel (Mexico) between 1984 and 2008, and provided a realistic hindcast of coral colony-scale (1-10 m) changing rugosity over the same period. We then projected future changes of Caribbean reef rugosity in response to global warming. Under severe and frequent thermal stress, the model predicted a dramatic loss of rugosity over the next two or three decades. Critically, reefs with managed parrotfish populations were able to delay the general loss of architectural complexity, as the benefits of grazing in maintaining living coral outweighed the bioerosion of dead coral skeletons. Overall, this model provides the first explicit projections of reef rugosity in a warming climate, and highlights the need of combining local (protecting and restoring high grazing) to global (mitigation of greenhouse gas emissions) interventions for the persistence of functional reef habitats. © 2014 John Wiley & Sons Ltd.

Integrating structure-from-motion photogrammetry with geospatial software as a novel technique for quantifying 3D ecological characteristics of coral reefs

PubMed Central

Delparte, D; Gates, RD; Takabayashi, M

2015-01-01

The structural complexity of coral reefs plays a major role in the biodiversity, productivity, and overall functionality of reef ecosystems. Conventional metrics with 2-dimensional properties are inadequate for characterization of reef structural complexity. A 3-dimensional (3D) approach can better quantify topography, rugosity and other structural characteristics that play an important role in the ecology of coral reef communities. Structure-from-Motion (SfM) is an emerging low-cost photogrammetric method for high-resolution 3D topographic reconstruction. This study utilized SfM 3D reconstruction software tools to create textured mesh models of a reef at French Frigate Shoals, an atoll in the Northwestern Hawaiian Islands. The reconstructed orthophoto and digital elevation model were then integrated with geospatial software in order to quantify metrics pertaining to 3D complexity. The resulting data provided high-resolution physical properties of coral colonies that were then combined with live cover to accurately characterize the reef as a living structure. The 3D reconstruction of reef structure and complexity can be integrated with other physiological and ecological parameters in future research to develop reliable ecosystem models and improve capacity to monitor changes in the health and function of coral reef ecosystems. PMID:26207190

Interactive effects of live coral and structural complexity on the recruitment of reef fishes

NASA Astrophysics Data System (ADS)

Coker, D. J.; Graham, N. A. J.; Pratchett, M. S.

2012-12-01

Corals reefs are subjected to multiple disturbances that modify levels of coral cover and structural complexity of the reef matrix, and in turn influence the structure of associated fish communities. With disturbances predicted to increase, insight into how changes in substrate condition will influence the recruitment of many fishes is essential for understanding the recovery of reef fish populations following biological and physical disturbances. While studies have revealed that both live coral cover and structural complexity are important for many fishes, there is a lack of understanding regarding how a combination of these changes will impact the recruitment of fishes. This study used experimentally constructed patch reefs consisting of six different habitat treatments; three levels of live coral cover (high, medium, low) crossed with two levels of structural complexity (high, low), to test the independent and combined effects of live coral cover and structural complexity on the recruitment and recovery of fish communities. The abundance and species diversity of fishes varied significantly among the six habitat treatments, but differences were not clearly associated with either coral cover or structural complexity and varied through time. More striking, however, was a significant difference in the composition of fish assemblages among treatments, due mostly to disproportionate abundance of coral-dwelling fishes on high coral cover, high complexity reefs. Overall, it appears that coral cover had a more important influence than structural complexity, at least for the contrasting levels of structural complexity achieved on experimental patch reefs. Furthermore, we found that live coral cover is important for the recruitment of some non-coral-dependent fishes. This study confirms that live coral cover is critical for the maintenance of high biodiversity on tropical coral reefs, and that sustained and ongoing declines in coral cover will adversely affect recruitment for many different species of reef fishes.

Elevated rates of morphological and functional diversification in reef-dwelling haemulid fishes.

PubMed

Price, Samantha A; Tavera, Jose J; Near, Thomas J; Wainwright, Peter C

2013-02-01

The relationship between habitat complexity and species richness is well established but comparatively little is known about the evolution of morphological diversity in complex habitats. Reefs are structurally complex, highly productive shallow-water marine ecosystems found in tropical (coral reefs) and temperate zones (rocky reefs) that harbor exceptional levels of biodiversity. We investigated whether reef habitats promote the evolution of morphological diversity in the feeding and locomotion systems of grunts (Haemulidae), a group of predominantly nocturnal fishes that live on both temperate and tropical reefs. Using phylogenetic comparative methods and statistical analyses that take into account uncertainty in phylogeny and the evolutionary history of reef living, we demonstrate that rates of morphological evolution are faster in reef-dwelling haemulids. The magnitude of this effect depends on the type of trait; on average, traits involved in the functional systems for prey capture and processing evolve twice as fast on reefs as locomotor traits. This result, along with the observation that haemulids do not exploit unique feeding niches on reefs, suggests that fine-scale trophic niche partitioning and character displacement may be driving higher rates of morphological evolution. Whatever the cause, there is growing evidence that reef habitats stimulate morphological and functional diversification in teleost fishes. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Barbados: Architecture and implications for accretion

NASA Astrophysics Data System (ADS)

Speed, R. C.; Larue, D. K.

1982-05-01

The island of Barbados exposes the crestal zone of the remarkably broad accretionary prism of the Lesser Antilles foreacrc. The architecture of Barbados is three-tiered: an upper arched cap of Pleistocene reefs that record rapid and differential uplift of the island, an intermediate zone of nappes of mainly abyssal or deep bathyal pelagic rocks, and a basal complex whose lithotypes extend to substantial depth and may be representative of the bulk of the western or inner accretionary prism. The exposed basal complex consists of generally steeply dipping ENE to NE-striking fault-bounded packets which contain rocks of one of three lithic suites: terrigenous (quartzose turbidite and mudstone), debris flow, and hemipelagic (chiefly radiolarite). Present but imcomplete rock dating indicates that the terrigenous and hemipelagic suites and the pelagic rocks of the intermediate zone are age overlapping in Early and Middle Eocene time. Deformation within packets of the basal complex is systematic, pre- or synfault, and indicative of shortening that is generally normal to packet boundaries. A unit of terrigenous materials that probably underwent local resedimentation in the Miocene is recognized in wells, but its relationship to exposed rocks is uncertain. The packet-bounding faults of the basal complex are interpreted to have been primary accretionary surfaces which may have been reactivated by later intraprism movements. Exposed sedimentary rocks of Barbados can be successfully assigned to contemporaneous depositional sites associated with an accretionary prism: terrigenous beds to a trench wedge that was connected to South American sediment sources, debris flow to trench floor or slope basin accumulations of material derived from the lower slope, hemipelagic to Atlantic plain strata, and pelagic rocks of the intermediate zone to deep outer forearc basin sites. The decollement at the base of the intermediate zone is probably due to uplift and arcward motion of the crestal zone of the accretionary prism with respect to the forearc basin during progressive prism growth. Principal uplift of the prism seems to have started, apparently abruptly, in the Miocene. Quaternary uplift of Barbados may be due partly to local diapirism. Paleogene subduction that created the arcward region of the prism probably occurred in a differently configured zone from the present one.

The influence of coral reef benthic condition on associated fish assemblages.

PubMed

Chong-Seng, Karen M; Mannering, Thomas D; Pratchett, Morgan S; Bellwood, David R; Graham, Nicholas A J

2012-01-01

Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae.

Shelters and Their Use by Fishes on Fringing Coral Reefs

PubMed Central

Ménard, Alexandre; Turgeon, Katrine; Roche, Dominique G.; Binning, Sandra A.; Kramer, Donald L.

2012-01-01

Coral reef fish density and species richness are often higher at sites with more structural complexity. This association may be due to greater availability of shelters, but surprisingly little is known about the size and density of shelters and their use by coral reef fishes. We quantified shelter availability and use by fishes for the first time on a Caribbean coral reef by counting all holes and overhangs with a minimum entrance diameter ≥3 cm in 30 quadrats (25 m2) on two fringing reefs in Barbados. Shelter size was highly variable, ranging from 42 cm3 to over 4,000,000 cm3, with many more small than large shelters. On average, there were 3.8 shelters m−2, with a median volume of 1,200 cm3 and a total volume of 52,000 cm3m−2. The number of fish per occupied shelter ranged from 1 to 35 individual fishes belonging to 66 species, with a median of 1. The proportion of shelters occupied and the number of occupants increased strongly with shelter size. Shelter density and total volume increased with substrate complexity, and this relationship varied among reef zones. The density of shelter-using fish was much more strongly predicted by shelter density and median size than by substrate complexity and increased linearly with shelter density, indicating that shelter availability is a limiting resource for some coral reef fishes. The results demonstrate the importance of large shelters for fish density and support the hypothesis that structural complexity is associated with fish abundance, at least in part, due to its association with shelter availability. This information can help identify critical habitat for coral reef fishes, predict the effects of reductions in structural complexity of natural reefs and improve the design of artificial reefs. PMID:22745664

Sedimentology and tectonics of the collision complex in the east arm of Sulawesi Indonesia

NASA Astrophysics Data System (ADS)

Simandjuntak, Tohap Oculair

An imbricated Mesozoic to Palaeogene continental margin sequence is juxtaposed with ophiolitic rocks in the East Arm of Sulawesi, Indonesia. The two tectonic terranes are bounded by the Batui Thrust and Balantak Fault System, which are considered to be the surface expression of the collision zone between the Banggai-Sula Platform and the Eastern Sulawesi Ophiolite Belt. The collision complex contains three distinctive sedimentary sequences : 1) Triassic-Palaeogene continental margin sediments, ii) Cretaceous pelagic sediments and iii) Neogene coarse clastic sediments and volcanogenic turbidites. (i) Late Triassic Lemo Beds consisting largely of carbonate-slope deposits and subsidiary clastics including quartz-rich lithic sandstones and lensoidal pebbly mudstone and conglomeratic breccia. The hemipelagic limestones are rich in micro-fossils. Some beds of the limestone contain bivalves and ammonites, including Misolia, which typifies the Triassic-Jurassic sequence of eastern Indonesia. The Jurassic Kapali Beds are dominated by quartzose arenites containing significant amounts of plant remains and lumps of coal. The Late Jurassic sediments consist of neritic carbonate deposits (Nambo Beds and Sinsidik Beds) containing ammonites and belemnites, including Belemnopsis uhligi Stevens, of Late Jurassic age. The Jurassic sediments are overlain unconformably by Late Cretaceous Luok Beds which are predominantly calcilutite with chert nodules rich in microfossils. The Luok Beds are unconformably overlain by the Palaeogene Salodik Limestones which consist of carbonate platform sediments rich in both benthic and planktonic foraminifera of Eocene to Early Miocene age. These sediments were deposited on the continental margin of the Banggai-Sula Platform. (ii) Deep-sea sediments (Boba Beds) consist largely of chert and subsidiary calcilutite rich in radiolaria of Cretaceous age. These rocks are part of an ophiolite suite. (iii) Coarse clastic sediments (Kolo Beds and Biak Conglomerates) are typical post-orogenic clastic rocks deposited on top of the collision complex. They are composed of material derived from both the continental margin sequence and ophiolite suite. Volcanogenic Lonsuit Turbidites occur in the northern part of the East Arm in Poh Head and unconformably overlie the ophiolite suite. Late Miocene to Pliocene planktonic foraminifera occur in the intercalated marlstone and marly sandstone beds within these rocks. The collision zone is marked by the occurrence of Kolokolo Melange, which contain exotic fragments detached from both the ophiolite suite and the continental margin sequence and a matrix of calcareous mudstone and marlstone rich in planktonic foraminifera of late Middle Miocene to Pliocene age. The melange is believed to have been formed during and after the collision of the Banggai-Sula Platform with the Eastern Sulawesi Ophiolite Belt. Hence, the collision event took place in Middle Miocene time. The occurrence of at least three terraces of Quaternary coraline reefs on the south coast of the East Arm of Sulawesi testifies to the rapid uplift of the region. Seismic data suggest that the collision might still be in progress at the present time.

Spring-summer diet of lake trout on Six Fathom Bank and Yankee Reef in Lake Huron

USGS Publications Warehouse

Madenjian, C.P.; Holuszko, J.D.; Desorcie, T.J.

2006-01-01

We examined the stomach contents of 1,045 lake trout (Salvelinus namaycush) caught on Six Fathom Bank and Yankee Reef, two offshore reef complexes in Lake Huron, during late spring and early summer 1998-2003. Lake trout ranged in total length from 213 to 858 mm, and in age from 2 to 14 years. In total, 742 stomachs contained food. On a wet-weight basis, alewife (Alosa pseudoharengus) dominated the spring-summer diet of lake trout on both of these offshore reef complexes. Alewives accounted for 75 to 90% of lake trout diet, depending on the lake trout size category. Size of alewives found in lake trout stomachs increased with increasing lake trout size. Faster growth of juvenile lake trout on Six Fathom Bank and Yankee Reef than on Sheboygan Reef in Lake Michigan was attributed to greater availability of small alewives on the offshore reefs in Lake Huron. Our findings indicated that alewives inhabited Six Fathom Bank and Yankee Reef during spring and summer months. Thus, our study provided support for the contention that alewives may have interfered with natural reproduction by lake trout on these offshore reef complexes in Lake Huron.

Neogene Proto-Caribbean porcupinefishes (Diodontidae)

PubMed Central

Aguilera, Orangel; Lopes, Ricardo Tadeu; Machado, Alessandra Silveira; dos Santos, Thaís Maria; Marques, Gabriela; Bertucci, Thayse; Aguiar, Thayanne; Carrillo-Briceño, Jorge; Rodriguez, Felix; Jaramillo, Carlos

2017-01-01

Fossil Diodontidae in Tropical America consist mostly of isolated and fused beak-like jawbones, and tooth plate batteries. These durophagous fishes are powerful shell-crushing predators on shallow water invertebrate faunas from Neogene tropical carbonate bottom, rocky reefs and surrounding flats. We use an ontogenetic series of high-resolution micro CT of fossil and extant species to recognize external and internal morphologic characters of jaws and tooth plate batteries. We compare similar sizes of jaws and/or tooth-plates from both extant and extinct species. Here, we describe three new fossil species including †Chilomycterus exspectatus n. sp. and †Chilomycterus tyleri n. sp. from the late Miocene Gatun Formation in Panama, and †Diodon serratus n. sp. from the middle Miocene Socorro Formation in Venezuela. Fossil Diodontidae review included specimens from the Neogene Basins of the Proto-Caribbean (Brazil: Pirabas Formation; Colombia: Jimol Formation, Panama: Gatun and Tuira formations; Venezuela: Socorro and Cantaure formations). Diodon is present in both the Atlantic and Pacific oceans, whereas the distribution of Chilomycterus is highly asymmetrical with only one species in the Pacific. It seems that Diodon was as abundant in the Caribbean/Western Atlantic during the Miocene as it is there today. We analyze the paleogeographic distribution of the porcupinefishes group in Tropical America, after the complete exhumation of the Panamanian isthmus during the Pliocene. PMID:28746370

High refuge availability on coral reefs increases the vulnerability of reef-associated predators to overexploitation.

PubMed

Rogers, Alice; Blanchard, Julia L; Newman, Steven P; Dryden, Charlie S; Mumby, Peter J

2018-02-01

Refuge availability and fishing alter predator-prey interactions on coral reefs, but our understanding of how they interact to drive food web dynamics, community structure and vulnerability of different trophic groups is unclear. Here, we apply a size-based ecosystem model of coral reefs, parameterized with empirical measures of structural complexity, to predict fish biomass, productivity and community structure in reef ecosystems under a broad range of refuge availability and fishing regimes. In unfished ecosystems, the expected positive correlation between reef structural complexity and biomass emerges, but a non-linear effect of predation refuges is observed for the productivity of predatory fish. Reefs with intermediate complexity have the highest predator productivity, but when refuge availability is high and prey are less available, predator growth rates decrease, with significant implications for fisheries. Specifically, as fishing intensity increases, predators in habitats with high refuge availability exhibit vulnerability to over-exploitation, resulting in communities dominated by herbivores. Our study reveals mechanisms for threshold dynamics in predators living in complex habitats and elucidates how predators can be food-limited when most of their prey are able to hide. We also highlight the importance of nutrient recycling via the detrital pathway, to support high predator biomasses on coral reefs. © 2018 by the Ecological Society of America.

Vulnerability of coral reef fisheries to a loss of structural complexity.

PubMed

Rogers, Alice; Blanchard, Julia L; Mumby, Peter J

2014-05-05

Coral reefs face a diverse array of threats, from eutrophication and overfishing to climate change. As live corals are lost and their skeletons eroded, the structural complexity of reefs declines. This may have important consequences for the survival and growth of reef fish because complex habitats mediate predator-prey interactions [1, 2] and influence competition [3-5] through the provision of prey refugia. A positive correlation exists between structural complexity and reef fish abundance and diversity in both temperate and tropical ecosystems [6-10]. However, it is not clear how the diversity of available refugia interacts with individual predator-prey relationships to explain emergent properties at the community scale. Furthermore, we do not yet have the ability to predict how habitat loss might affect the productivity of whole reef communities and the fisheries they support. Using data from an unfished reserve in The Bahamas, we find that structural complexity is associated not only with increased fish biomass and abundance, but also with nonlinearities in the size spectra of fish, implying disproportionately high abundances of certain size classes. By developing a size spectrum food web model that links the vulnerability of prey to predation with the structural complexity of a reef, we show that these nonlinearities can be explained by size-structured prey refugia that reduce mortality rates and alter growth rates in different parts of the size spectrum. Fitting the model with data from a structurally complex habitat, we predict that a loss of complexity could cause more than a 3-fold reduction in fishery productivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cenozoic evolution of the Socotra Island: opening of the Gulf of Aden

NASA Astrophysics Data System (ADS)

Razin, P.; Robin, C.; Serra Kiel, J.; Leroy, S.; Bellahsen, N.; Khanbari, K.

2009-12-01

A complete stratigraphic and geological map revision of the Tertiary of Socotra Island is undertaken in order to better characterize the geometry and the tecto-sedimentary evolution of the southern margin of the Gulf of Aden, and compare them with those of the conjugate northern margin in Oman. An increase of the rate of subsidence is recorded during the Late Eocene and is associated with a transgressive peak within carbonate platform deposits (Aydim Fm.). At the scale of the Arabian plate, the extent of this platform is reduced to the future rift area. This evolution of the platform system shows a modification of the sedimentary profiles, controlled by the beginning of the rifting. The syn-rift deposits of the Early Oligocene correspond to sub-reef carbonate platform facies (Ashawq Fm.). First, the throw of synsedimentary faults and the movements linked with differential subsidence are widely compensated by carbonate production which manages to maintain a platform profile. These movements are recorded by thickness variations, significant lateral variations in the platform facies and by a local inversion of sedimentary polarities controlled by the tilting of faulted blocks. Like on the northern margin, an acceleration of the extension process leads, during the Late Oligocene, to a collapse of the platform and to the creation of deep sub-basins with carbonate gravity-flow sedimentation. Marginal reef platforms keep growing at this stage on the structural highs and feed gravity-flow sedimentary systems. The sedimentation rate stays then relatively low in the basin, forming a complex topography of the margin, marked by a segmentation into numerous sub-basins more or less connected and separated by submarine escarpments marked by wedges of breccia deposits along active normal faults. In different points, these faults are sealed by sedimentary deposits characterized by progressive unconformities and onlap geometries on the fault escarpments. These geometries show the relatively short length of the phase of « stretching » of the continental crust. Around the end of the Early Miocene, the progradation of conglomerate fan-delta deposits locally results in the fill of the basins and shows a major phase of uplift. It is very rapidly followed by a new phase of subsidence which allows the preservation of thick fan-delta and equivalent reef platform complex unconformably overlying different units of the syn-rift and pre-rift sequences, or even the exhumed Proterozoic basement. This tectonic-sedimentary phase is interpreted as synchronous to the continental breakup and the onset of the OCT at the foot of the margin. The analogy with the phase of development of «sag basins» on the Atlantic margins has to be analyzed. This major uplift at the transition syn-rift/post-rift seems to be expressed symmetrically on both margins. These syn-OCT deposits are then uplifted and affected by late tilting events. However, the most recent deposits, probably Late Miocene to plio-Quaternary in age, have only been affected by small uplifts, unlike those of the Dhofar on the northern margin

The Influence of Coral Reef Benthic Condition on Associated Fish Assemblages

PubMed Central

Chong-Seng, Karen M.; Mannering, Thomas D.; Pratchett, Morgan S.; Bellwood, David R.; Graham, Nicholas A. J.

2012-01-01

Accumulative disturbances can erode a coral reef’s resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae. PMID:22870294

Petroleum prospects for offshore sedimentary basins in the eastern Papua New Guinea and Solomon Islands regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruns, T.R.; Vedder, J.G.

Intra-arc basins in the Buka-Bougainville region of Papua New Guinea and in the Solomon Islands contain thick sedimentary sequences that may be prospective for petroleum. The Queen Emma basin, between Bougainville and New Ireland, contains as much as 8 km of deformed Oligocene and younger strata. The Central Solomons Trough, which underlies New Georgia Sound, is a composite intra-arc basin that contains late Oligocene and younger strata as much as 7 km thick. Farther east, beneath Indispensable Strait, the down-faulted Indispensable basin locally contains as much as 5.4 km of Miocene( ) and younger strata, and the offshore part ofmore » Mbokokimbo basin off eastern Guadalcanal includes 6 km or more of late Miocene and younger strata. All of these basins have some of the attributes necessary to generate and trap petroleum. Structural and stratigraphic traps are common, including faulted anticlines, sedimentary wedges, and carbonate reefs and reef-derived deposits on submarine ridges and along the basin margins. The thickness of the basin deposits ensures that some strata are buried deeply enough to be within the thermal regime required for hydrocarbon generation. However, little source or reservoir rock information is available because of the lack of detailed surface and subsurface stratigraphy. Moreover, much of the basin sediment is likely to consist of volcaniclastic material, derived from uplifted volcanogenic rocks surrounding the basins, and may be poor in source and reservoir rocks. Until additional stratigraphic information is available, analysis of the petroleum potential of these basins is a matter of conjecture.« less

Cryptic Coral Reef Diversity Across the Pacific Assessed using Autonomous Reef Monitoring Structures and Multi-omic Methods

NASA Astrophysics Data System (ADS)

Ransome, E. J.; Timmers, M.; Hartmann, A.; Collins, A.; Meyer, C.

2016-02-01

Coral reefs harbor diverse and distinct eukaryotic, bacterial and viral communities, which are critically important for their success. The lack of standardized measures for comprehensively assessing reef diversity has been a major obstacle in understanding the complexity of eukaryotic and microbial associations, and the processes that drive ecosystem shifts on reefs. ARMS, which mimic the structural complexity of the reef using artificial settlement plates, were used to systematically measure reef biodiversity across the Indo-Pacific. This device allows for standardized sampling of reef microbes to metazoans, providing the opportunity to investigate the fundamental links between these groups at an ecosystem level. We integrate the use of traditional ecology methods with metagenomics and metabolomics (metabolic predictors) to quantify the taxonomic composition of one of the planet's most diverse ecosystems and to assess the fundamental links between these cryptic communities and ecosystem function along geographical and anthropogenic stress gradients.

LIDAR optical rugosity of coral reefs in Biscayne National Park, Florida

USGS Publications Warehouse

Brock, J.C.; Wright, C.W.; Clayton, T.D.; Nayegandhi, A.

2004-01-01

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Rotran), and the average elevation difference between adjacent points (Av(??E ap)). Further, the whole-site mean and maximum values of Ro tran and Av(??Eap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs. ?? Springer-Verlag 2004.

The Role of Faulting on the Growth of a Carbonate Platform: Evidence from 3D Seismic Analysis and Section Restoration

NASA Astrophysics Data System (ADS)

Nur Fathiyah Jamaludin, Siti; Pubellier, Manuel; Prasad Ghosh, Deva; Menier, David; Pierson, Bernard

2014-05-01

Tectonics in addition to other environmental factors impacts the growth of carbonate platforms and plays an important role in shaping the internal architecture of the platforms. Detailed of faults and fractures development and healing in carbonate environment have not been explored sufficiently. Using 3D seismic and well data, we attempt to reconstruct the structural evolution of a Miocene carbonate platform in Central Luconia Province, offshore Malaysia. Luconia Province is located in the NW coast of Borneo and has become one of the largest carbonate factories in SE Asia. Seismic interpretations including seismic attribute analysis are applied to the carbonate platform to discern its sedimentology and structural details. Detailed seismic interpretations highlight the relationships of carbonate deposition with syn-depositional faulting. Branching conjugate faults are common in this carbonate platform and have become a template for reef growth, attesting lateral facies changes within the carbonate environments. Structural restoration was then appropriately performed on the interpreted seismic sections based on sequential restoration techniques, and provided images different from those of horizon flattening methods. This permits us to compensate faults' displacement, remove recent sediment layers and finally restore the older rock units prior to the fault motions. It allows prediction of platform evolution as a response to faulting before and after carbonate deposition and also enhances the pitfalls of interpretation. Once updated, the reconstructions allow unravelling of the un-seen geological features underneath the carbonate platform, such as paleo-structures and paleo-topography which in turn reflects the paleo-environment before deformations took place. Interestingly, sections balancing and restoration revealed the late-phase (Late Oligocene-Early Miocene) rifting of South China Sea, otherwise difficult to visualize on seismic sections. Later it is shown that this carbonate platform was possibly originated from two or more connected reef build-ups. The platform evolution in terms of tectonic influences on carbonate growth and development may serve as a case example for re-evaluation of pre-Late Miocene structures as a new potential target for hydrocarbon exploration in Central Luconia Province. Eventually, techniques used in this study might be of interest to oil and gas explorers in carbonate system.

Coral reef recovery dynamics in a changing world

NASA Astrophysics Data System (ADS)

Graham, N. A. J.; Nash, K. L.; Kool, J. T.

2011-06-01

Coral reef ecosystems are degrading through multiple disturbances that are becoming more frequent and severe. The complexities of this degradation have been studied in detail, but little work has assessed characteristics that allow reefs to bounce back and recover between pulse disturbance events. We quantitatively review recovery rates of coral cover from pulse disturbance events among 48 different reef locations, testing the relative roles of disturbance characteristics, reef characteristics, connectivity and anthropogenic influences. Reefs in the western Pacific Ocean had the fastest recovery, whereas reefs in the geographically isolated eastern Pacific Ocean were slowest to recover, reflecting regional differences in coral composition, fish functional diversity and geographic isolation. Disturbances that opened up large areas of benthic space recovered quickly, potentially because of nonlinear recovery where recruitment rates were high. The type of disturbance had a limited effect on subsequent rates of reef recovery, although recovery was faster following crown-of-thorns starfish outbreaks. This inconsequential role of disturbance type may be in part due to the role of unaltered structural complexity in maintaining key reef processes, such as recruitment and herbivory. Few studies explicitly recorded potential ecological determinants of recovery, such as recruitment rates, structural complexity of habitat and the functional composition of reef-associated fish. There was some evidence of slower recovery rates within protected areas compared with other management systems and fished areas, which may reflect the higher initial coral cover in protected areas rather than reflecting a management effect. A better understanding of the driving role of processes, structural complexity and diversity on recovery may enable more appropriate management actions that support coral-dominated ecosystems in our changing climate.

Mesopredator trophodynamics on thermally stressed coral reefs

NASA Astrophysics Data System (ADS)

Hempson, Tessa N.; Graham, Nicholas A. J.; MacNeil, M. Aaron; Hoey, Andrew S.; Almany, Glenn R.

2018-03-01

Ecosystems are becoming vastly modified through disturbance. In coral reef ecosystems, the differential susceptibility of coral taxa to climate-driven bleaching is predicted to shift coral assemblages towards reefs with an increased relative abundance of taxa with high thermal tolerance. Many thermally tolerant coral species are characterised by low structural complexity, with reduced habitat niche space for the small-bodied coral reef fishes on which piscivorous mesopredators feed. This study used a patch reef array to investigate the potential impacts of climate-driven shifts in coral assemblages on the trophodynamics of reef mesopredators and their prey communities. The `tolerant' reef treatment consisted only of coral taxa of low susceptibility to bleaching, while `vulnerable' reefs included species of moderate to high thermal vulnerability. `Vulnerable' reefs had higher structural complexity, and the fish assemblages that established on these reefs over 18 months had higher species diversity, abundance and biomass than those on `tolerant' reefs. Fish assemblages on `tolerant' reefs were also more strongly influenced by the introduction of a mesopredator ( Cephalopholis boenak). Mesopredators on `tolerant' reefs had lower lipid content in their muscle tissue by the end of the 6-week experiment. Such sublethal energetic costs can compromise growth, fecundity, and survivorship, resulting in unexpected population declines in long-lived mesopredators. This study provides valuable insight into the altered trophodynamics of future coral reef ecosystems, highlighting the potentially increased vulnerability of reef fish assemblages to predation as reef structure declines, and the cost of changing prey availability on mesopredator condition.

Relative Importance of Coral Cover, Habitat Complexity and Diversity in Determining the Structure of Reef Fish Communities

PubMed Central

Komyakova, Valeriya; Munday, Philip L.; Jones, Geoffrey P.

2013-01-01

The structure of coral reef habitat has a pronounced influence on the diversity, composition and abundance of reef-associated fishes. However, the particular features of the habitat that are most critical are not always known. Coral habitats can vary in many characteristics, notably live coral cover, topographic complexity and coral diversity, but the relative effects of these habitat characteristics are often not distinguished. Here, we investigate the strength of the relationships between these habitat features and local fish diversity, abundance and community structure in the lagoon of Lizard Island, Great Barrier Reef. In a spatial comparison using sixty-six 2m2 quadrats, fish species richness, total abundance and community structure were examined in relation to a wide range of habitat variables, including topographic complexity, habitat diversity, coral diversity, coral species richness, hard coral cover, branching coral cover and the cover of corymbose corals. Fish species richness and total abundance were strongly associated with coral species richness and cover, but only weakly associated with topographic complexity. Regression tree analysis showed that coral species richness accounted for most of the variation in fish species richness (63.6%), while hard coral cover explained more variation in total fish abundance (17.4%), than any other variable. In contrast, topographic complexity accounted for little spatial variation in reef fish assemblages. In degrading coral reef environments, the potential effects of loss of coral cover and topographic complexity are often emphasized, but these findings suggest that reduced coral biodiversity may ultimately have an equal, or greater, impact on reef-associated fish communities. PMID:24349455

Relative importance of coral cover, habitat complexity and diversity in determining the structure of reef fish communities.

PubMed

Komyakova, Valeriya; Munday, Philip L; Jones, Geoffrey P

2013-01-01

The structure of coral reef habitat has a pronounced influence on the diversity, composition and abundance of reef-associated fishes. However, the particular features of the habitat that are most critical are not always known. Coral habitats can vary in many characteristics, notably live coral cover, topographic complexity and coral diversity, but the relative effects of these habitat characteristics are often not distinguished. Here, we investigate the strength of the relationships between these habitat features and local fish diversity, abundance and community structure in the lagoon of Lizard Island, Great Barrier Reef. In a spatial comparison using sixty-six 2m(2) quadrats, fish species richness, total abundance and community structure were examined in relation to a wide range of habitat variables, including topographic complexity, habitat diversity, coral diversity, coral species richness, hard coral cover, branching coral cover and the cover of corymbose corals. Fish species richness and total abundance were strongly associated with coral species richness and cover, but only weakly associated with topographic complexity. Regression tree analysis showed that coral species richness accounted for most of the variation in fish species richness (63.6%), while hard coral cover explained more variation in total fish abundance (17.4%), than any other variable. In contrast, topographic complexity accounted for little spatial variation in reef fish assemblages. In degrading coral reef environments, the potential effects of loss of coral cover and topographic complexity are often emphasized, but these findings suggest that reduced coral biodiversity may ultimately have an equal, or greater, impact on reef-associated fish communities.

Sequence stratigraphy of upper Paleogene to Neogene carbonates exposed from Guánica bay to Guayanilla, Southern Puerto Rico.

NASA Astrophysics Data System (ADS)

Flores Hots, V. E.; Santos, H.

2016-12-01

Detailed stratigraphic columns were measured and microfacies analysis was performed in southwestern Puerto Rico to conduct a sequence stratigraphic analysis of Paleogene to Neogene strata. Two of the best exposed outcrops include the Guánica Bay and outcrops along Highway PR-132 in Guayanilla. Three depositional sequences, separated by two major sequence boundaries were found. The lower sequence occurs within the Juana Díaz Formation and is an open shelf to reef facies indicative of a Transgressive System Tract (TST), that is overlain by a High Stand System Tract (HST) marked by reef progradation. The HST in both Guánica Bay and Guayanilla is characterized by coral-rhodolith cyclicity however sections in Guánica Bay show pervasive recrystallization due to diagenetic alteration as a result of a long periods of exposure. This first sequence is Oligocene in age. The middle sequence, exposed at the eastern section of the Guánica Bay is also part of the Juana Díaz Formation and includes a turbiditic Lowstand System Tract (LST) of slope-like deposits flow, a TST constituted by coral rubble and skeletal grainstones belonging to a shallow island slope environment; and a HST that consists of an island slope chalk facies intercalated with turbidite grainstones derived storm events at the Guayanilla location. During the deposition of the middle sequence the Guánica Bay west section was topographically higher and exposed. The upper depositional sequence is Miocene in age and is composed of a TST with the transgression starting distally in the Guánica area and transgressing northward toward the Guayanilla area. These was correlated using high resolution 87Sr/86Sr isotope concentrations of shallow marine mollusks Kuphus incrassatus in the Ponce Formation at the Guánica Bay and Guayanilla locations. Facies patterns like the ones in the studied outcrops of southwestern Puerto Rico provide an exemplary environmental model of variability of paleodepositional relief, tectonic setting, variability in depositional setting of reef Sediment acumulations, the influence of storm events and variability in rock porosity by diagenetic processes yielding valuable models that may apply to potential Oligocene - Miocene hydrocarbon reservoirs.

Palaeoecological records of coral community development on a turbid, nearshore reef complex: baselines for assessing ecological change

NASA Astrophysics Data System (ADS)

Johnson, J. A.; Perry, C. T.; Smithers, S. G.; Morgan, K. M.; Santodomingo, N.; Johnson, K. G.

2017-09-01

Understanding past coral community development and reef growth is crucial for placing contemporary ecological and environmental change within appropriate reef-building timescales. On Australia's Great Barrier Reef (GBR), coral reefs situated within coastal inner-shelf zones are a particular priority. This is due to their close proximity to river point sources, and therefore susceptibility to reduced water quality discharged from coastal catchments, many of which have been modified following European settlement (ca. 1850 AD). However, the extent of water-quality decline and its impacts on the GBR's inner-shelf reefs remain contentious. In this study, palaeoecological coral assemblage records were developed for five proximal coral reefs situated within a nearshore turbid-zone reef complex on the central GBR. A total of 29 genera of Scleractinia were identified from the palaeoecological inventory of the reef complex, with key contributions to reef-building made by Acropora, Montipora, and Turbinaria. Discrete intervals pre- and post-dating European settlement, but associated with equivalent water depths, were identified using Bayesian age-depth modelling, enabling investigation of competing ideas of the main drivers of nearshore coral assemblage change. Specifically, we tested the hypotheses that changes in the composition of nearshore coral assemblages are: (1) intrinsically driven and linked to vertical reef development towards sea level, and (2) the result of changes in water quality associated with coastal river catchment modification. Our records found no discernible evidence of change in the generic composition of coral assemblages relative to European settlement. Instead, two distinctive depth-stratified assemblages were identified. This study demonstrates the robust nature of nearshore coral communities under reported water-quality decline and provides a useful context for the monitoring and assessment of ecological change on reefs located within the most nearshore turbid-zone environments of the central GBR.

Relative and combined effects of habitat and fishing on reef fish communities across a limited fishing gradient at Ningaloo.

PubMed

Wilson, Shaun K; Babcock, Russ C; Fisher, Rebecca; Holmes, Thomas H; Moore, James A Y; Thomson, Damian P

2012-10-01

Habitat degradation and fishing are major drivers of temporal and spatial changes in fish communities. The independent effects of these drivers are well documented, but the relative importance and interaction between fishing and habitat shifts is poorly understood, particularly in complex systems such as coral reefs. To assess the combined and relative effects of fishing and habitat we examined the composition of fish communities on patch reefs across a gradient of high to low structural complexity in fished and unfished areas of the Ningaloo Marine Park, Western Australia. Biomass and species richness of fish were positively correlated with structural complexity of reefs and negatively related to macroalgal cover. Total abundance of fish was also positively related to structural complexity, however this relationship was stronger on fished reefs than those where fishing is prohibited. The interaction between habitat condition and fishing pressure is primarily due to the high abundance of small bodied planktivorous fish on fished reefs. However, the influence of management zones on the abundance and biomass of predators and target species is small, implying spatial differences in fishing pressure are low and unlikely to be driving this interaction. Our results emphasise the importance of habitat in structuring reef fish communities on coral reefs especially when gradients in fishing pressure are low. The influence of fishing effort on this relationship may however become more important as fishing pressure increases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Anticipative management for coral reef ecosystem services in the 21st century.

PubMed

Rogers, Alice; Harborne, Alastair R; Brown, Christopher J; Bozec, Yves-Marie; Castro, Carolina; Chollett, Iliana; Hock, Karlo; Knowland, Cheryl A; Marshell, Alyssa; Ortiz, Juan C; Razak, Tries; Roff, George; Samper-Villarreal, Jimena; Saunders, Megan I; Wolff, Nicholas H; Mumby, Peter J

2015-02-01

Under projections of global climate change and other stressors, significant changes in the ecology, structure and function of coral reefs are predicted. Current management strategies tend to look to the past to set goals, focusing on halting declines and restoring baseline conditions. Here, we explore a complementary approach to decision making that is based on the anticipation of future changes in ecosystem state, function and services. Reviewing the existing literature and utilizing a scenario planning approach, we explore how the structure of coral reef communities might change in the future in response to global climate change and overfishing. We incorporate uncertainties in our predictions by considering heterogeneity in reef types in relation to structural complexity and primary productivity. We examine 14 ecosystem services provided by reefs, and rate their sensitivity to a range of future scenarios and management options. Our predictions suggest that the efficacy of management is highly dependent on biophysical characteristics and reef state. Reserves are currently widely used and are predicted to remain effective for reefs with high structural complexity. However, when complexity is lost, maximizing service provision requires a broader portfolio of management approaches, including the provision of artificial complexity, coral restoration, fish aggregation devices and herbivore management. Increased use of such management tools will require capacity building and technique refinement and we therefore conclude that diversification of our management toolbox should be considered urgently to prepare for the challenges of managing reefs into the 21st century. © 2014 John Wiley & Sons Ltd.

Oceanic forcing of coral reefs.

PubMed

Lowe, Ryan J; Falter, James L

2015-01-01

Although the oceans play a fundamental role in shaping the distribution and function of coral reefs worldwide, a modern understanding of the complex interactions between ocean and reef processes is still only emerging. These dynamics are especially challenging owing to both the broad range of spatial scales (less than a meter to hundreds of kilometers) and the complex physical and biological feedbacks involved. Here, we review recent advances in our understanding of these processes, ranging from the small-scale mechanics of flow around coral communities and their influence on nutrient exchange to larger, reef-scale patterns of wave- and tide-driven circulation and their effects on reef water quality and perceived rates of metabolism. We also examine regional-scale drivers of reefs such as coastal upwelling, internal waves, and extreme disturbances such as cyclones. Our goal is to show how a wide range of ocean-driven processes ultimately shape the growth and metabolism of coral reefs.

Airborne lidar sensing of massive stony coral colonies on patch reefs in the northern Florida reef tract

USGS Publications Warehouse

Brock, J.C.; Wright, C.W.; Kuffner, I.B.; Hernandez, R.; Thompson, P.

2006-01-01

In this study we examined the ability of the NASA Experimental Advanced Airborne Research Lidar (EAARL) to discriminate cluster zones of massive stony coral colonies on northern Florida reef tract (NFRT) patch reefs based on their topographic complexity (rugosity). Spatially dense EAARL laser submarine topographic soundings acquired in August 2002 were used to create a 1-m resolution digital rugosity map for adjacent NFRT study areas characterized by patch reefs (Region A) and diverse substratums (Region B). In both regions, sites with lidar-sensed rugosities above 1.2 were imaged by an along-track underwater videography system that incorporated the acquisition of instantaneous GPS positions. Subsequent manual interpretation of videotape segments was performed to identify substratum types that caused elevated lidar-sensed rugosity. Our study determined that massive coral colony formation, modified by subsequent physical and biological processes that breakdown patch reef framework, was the primary source of topographic complexity sensed by the EAARL in the NFRT. Sites recognized by lidar scanning to be topographically complex preferentially occurred around the margins of patch reefs, constituted a minor fraction of the reef system, and usually reflected the presence of massive coral colonies in cluster zones, or their derivatives created by mortality, bioerosion, and physical breakdown.

An anomalous Pt-Pd occurrence below the JM reef, Stillwater Complex, Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

McIlveen, C.L.

1993-04-01

The late Archean Stillwater Complex, in south-central Montana, consists of the Basal, Ultramafic, and Banded series. The Lower Banded series contains several anomalous platinum-group element (PGE) occurrences, with the JM reef having the highest values (an average of 6,250 ppb Pt and 24,000 ppb Pd) and greatest lateral persistence. The Coors anomaly, below the reef, is near the middle of the complex. This zone contains bronzite cumulates which range from 100--14,600 ppb Pt, with an average of 1,250 ppb. Pt:Pd ratios in the Coors zone average 1:1.7, compared to 1:3.8 in the reef. Sulfides associated with the PGE's show immisciblemore » textures indicating a magmatic origin similar to the reef. The anomaly lies approximately 200 m below the reef along the Banded-Ultramafic series contact where the Gabbronorite 1 zone is virtually absent. Layering between the reef and the Ultramafic series bronzitite is irregular and thin compared to the normal 400-m thickness exposed elsewhere in the complex. Bronzitites which contain the PGE's are podiform and often pegmatoidal. Norites adjacent to the bronzities also tend to be pegmatoidal and sulfide-bearing, but contain an average of only 75 ppb Pt. Microprobe analyses of bronzites in this zone show abruptly lower Mg/(Mg + Fe) of 0.77 compared to 0.83 in the uppermost bronzitite. The disrupted layering and thinning in the Coors area may have formed by slumping, scouring, or thermal erosion in the cumulate pile during crystallization. Coors mineralization may have developed through processes similar to those in the JM reef. However, occurrence of the coors mineralization with irregular layering and higher PGE ratios suggest an origin different than that in the reef.« less

Occlusal enamel complexity in middle miocene to holocene equids (Equidae: Perissodactyla) of North America.

PubMed

Famoso, Nicholas A; Davis, Edward Byrd

2014-01-01

Four groups of equids, "Anchitheriinae," Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the complexity of occlusal patterns. We used analyses of variance and an analysis of co-variance to test whether equid teeth increase resistive cutting area for food processing during mastication, as expressed in occlusal enamel complexity, in response to increased abrasion in their diet. Results suggest that occlusal enamel complexity was influenced by climate, phylogeny, and tooth position through time. Occlusal enamel complexity in middle Miocene to Modern horses increased as the animals experienced increased tooth abrasion and a cooling climate.

Occlusal Enamel Complexity in Middle Miocene to Holocene Equids (Equidae: Perissodactyla) of North America

PubMed Central

Famoso, Nicholas A.; Davis, Edward Byrd

2014-01-01

Four groups of equids, “Anchitheriinae,” Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the complexity of occlusal patterns. We used analyses of variance and an analysis of co-variance to test whether equid teeth increase resistive cutting area for food processing during mastication, as expressed in occlusal enamel complexity, in response to increased abrasion in their diet. Results suggest that occlusal enamel complexity was influenced by climate, phylogeny, and tooth position through time. Occlusal enamel complexity in middle Miocene to Modern horses increased as the animals experienced increased tooth abrasion and a cooling climate. PMID:24587267

Long-lived groupers require structurally stable reefs in the face of repeated climate change disturbances

NASA Astrophysics Data System (ADS)

Karkarey, R.; Kelkar, N.; Lobo, A. Savio; Alcoverro, T.; Arthur, R.

2014-06-01

Benthic recovery from climate-related disturbances does not always warrant a commensurate functional recovery for reef-associated fish communities. Here, we examine the distribution of benthic groupers (family Serranidae) in coral reef communities from the Lakshadweep archipelago (Arabian Sea) in response to structural complexity and long-term habitat stability. These coral reefs that have been subject to two major El Niño Southern Oscillation-related coral bleaching events in the last decades (1998 and 2010). First, we employ a long-term (12-yr) benthic-monitoring dataset to track habitat structural stability at twelve reef sites in the archipelago. Structural stability of reefs was strongly driven by exposure to monsoon storms and depth, which made deeper and more sheltered reefs on the eastern aspect more stable than the more exposed (western) and shallower reefs. We surveyed groupers (species richness, abundance, biomass) in 60 sites across the entire archipelago, representing both exposures and depths. Sites were selected along a gradient of structural complexity from very low to high. Grouper biomass appeared to vary with habitat stability with significant differences between depth and exposure; sheltered deep reefs had a higher grouper biomass than either sheltered shallow or exposed (deep and shallow) reefs. Species richness and abundance showed similar (though not significant) trends. More interestingly, average grouper biomass increased exponentially with structural complexity, but only at the sheltered deep (high stability) sites, despite the availability of recovered structure at exposed deep and shallow sites (lower-stability sites). This trend was especially pronounced for long-lived groupers (life span >10 yrs). These results suggest that long-lived groupers may prefer temporally stable reefs, independent of the local availability of habitat structure. In reefs subject to repeated disturbances, the presence of structurally stable reefs may be critical as refuges for functionally important, long-lived species like groupers.

A palynostratigraphic approach to the SW Anatolian molasse basin: Kale-Tavas molasse and Denizli molasse

NASA Astrophysics Data System (ADS)

Akgün, Funda; Sözbilir, Hasan

The study, explains stratigraphy of the Oligo-Miocene molasse around the Denizli province (SW Anatolia), based on the palynology which is also supported by the detailed mapping and correlation of the measured sections from the coal-bearing sequences of the molasse deposits. For this purpose, two huge depressions named as the Kale-Tavas molasse and Denizli molasse basins were examined. The Kale-Tavas molasse deposits has a basal unconformity with the underlying pre-Oligocene basement and begins with the Chattian Karadere and Mortuma formations which are covered unconformably by the Aquitanian Yenidere formation. An angular unconformity between the Chattian and the Burdigalian is only observed in the middle part of the basin, around Kale. In the Tavas section, the Aquitanian and the Burdigalian are absent. The Denizli molasse is characterized by Chattian-Aquitanian sequence consisting of distinctive sedimentary facies, alluvial fan and deltaic-shallow marine deposits with carbonate patch reefs. Palynostratigraphic studies, which have given the Chattian age, have been carried out from the coal lenses of alluvial fan and delta plain deposits. In addition to the palynological determinations, coral and foraminiferal content of the carbonate patch reefs which rest conformably on the coal-bearing sequences have yielded the Chattian-Aquitanian age. Two different palynomorph associations have been determined from the molasse deposits. The first palynomorph association which is established in the samples from the Sağdere and Mortuma formations, corresponds to the Chattian age, whilst the second is of the Aquitanian age. The Late Oligocene-Early Miocene which is claimed as the time of N-S-extensional tectonics in western Turkey, is related to the depositional time of the molasse sequences in the study area. Thus, the molasse is older than the basal deposits of the Gediz and Büyük Menderes grabens.

From Submarine Volcanoes to Modern Atolls: New Insights from the Mozambique Channel (SW Indian Ocean)

NASA Astrophysics Data System (ADS)

Jorry, S.; Courgeon, S.; Camoin, G.; BouDagher-Fadel, M.; Jouet, G.; Poli, E.

2016-12-01

Although the long-term evolution of isolated shallow-water carbonate platforms leading to guyot and atoll formation has been the subject of numerous studies during the last decades, their driving processes are still the subject of active debates. The Mozambique Channel (SW Indian Ocean) is characterized by several modern carbonate platforms, ranging from 11°S to 21°S in latitudes. These platforms are characterized by reef margins mostly developed on windward sides with internal parts blanketed by sand dunes and numerous reef pinnacles, or by Darwin-type atolls with enclosed lagoons. Dredge sampling, underwater observations and geophysical acquisitions carried out during recent oceanographic cruises (PTOLEMEE and PAMELA-MOZ1) along slopes and basins adjacent to modern platforms led to the discovery of flat-top seamounts corresponding to shallow-water carbonate platforms which grew on top of submarine volcanoes. Microfacies and datings (biostratigraphy analysis coupled with Strontium isotopic stratigraphy) indicate that those carbonate platforms, characterized by fauna assemblages dominated by corals, Halimeda and red algaes, and larger benthic foraminifera, developed in tropical settings from Early Miocene to Late Miocene/Early Pliocene times. Submarine volcanism, karstification and pedogenesis evidences on top of the drowned edifices demonstrate that tectonic deformation, rejuvenated volcanic activity and subaerial exposure occurred after and potentially during the Neogene platform aggradation. Growth of modern platforms on top of submerged carbonate terraces is explained by topographic irregularities inherited from volcanism, tectonic and/or subaerial exposure conditions which could have produced favorable substratum for carbonates which grew during the Plio-Quaternary, up to reach modern sea-level. This research is co-funded by TOTAL and IFREMER as part of the PAMELA (Passive Margin Exploration Laboratories) scientific project.

Quantitative controls on location and architecture of carbonate depositional sequences: Upper miocene, cabo de gata region, SE Spain

USGS Publications Warehouse

Franseen, E.K.; Goldstein, R.H.; Farr, M.R.

1997-01-01

Sequence stratigraphy, pinning-point relative sea-level curves, and magnetostratigraphy provide the quantitative data necessary to understand how rates of sea-level change and different substrate paleoslopes are dominant controls on accumulation rate, carbonate depositional sequence location, and internal architecture. Five third-order (1-10 my) and fourth-order (0.1-1.0 my) upper Miocene carbonate depositional sequences (DS1A, DS1B, DS2, DS3, TCC) formed with superimposed higher-frequency sea-level cycles in an archipelago setting in SE Spain. Overall, our study indicates when areas of high substrate slope (> 15??) are in shallow water, independent of climate, the location and internal architecture of carbonate deposits are not directly linked to sea-level position but, instead, are controlled by location of gently sloping substrates and processes of bypass. In contrast, if carbonate sediments are generated where substrates of low slope ( 15.6 cm/ky to ??? 2 cm/ky and overall relative sea level rose at rates of 17-21.4 cm/ky. Higher frequency sea-level rates were about 111 to more than 260 cm/ky, producing onlapping, fining- (deepening-) upward cycles. Decreasing accumulation rates resulted from decreasing surface area for shallow-water sediment production, drowning of shallow-water substrates, and complex sediment dispersal related to the archipelago setting. Typical systems tract and parasequence development should not be expected in "bypass ramp" settings; facies of onlapping strata do not track base level and are likely to be significantly different compared to onlapping strata associated with coastal onlap. Basal and upper DS2 reef megabreccias (indicating the transition from cool to warmer climatic conditions) were eroded from steep upslope positions and redeposited downslope onto areas of gentle substrate during rapid sea-level falls (> 22.7 cm/ky) of short duration. Such rapid sea-level falls and presence of steep slopes are not conducive to formation of forced regressive systems tracts composed of down-stepping reef clinoforms. The DS3 reefal platform formed where shallow water coincided with gently sloping substrates created by earlier deposition. Slow progradation (0.39-1.45 km/my) is best explained by the lack of an extensive bank top, progressively falling sea level, and low productivity resulting from siliciclastic debris and excess nutrients shed from nearby volcanic islands. Although DS3 strata were deposited during a third-order relative sea-level cycle, a typical transgressive systems tract is not recognizable, indicating that the initial relative rise in sea level was too rapid (??? 19 cm/ky). Downstepping reefs, forming a forced regressive systems tract, were deposited during the relative sea-level fall at the end of DS3, indicating that relatively slow rates of fall (10 cm/ky or less) over favorable paleoslope conditions are conducive to generation of forced regressive systems tracts consisting of downstepping reef clinoforms. The TCC sequence consists of four shallow-water sedimentary cycles that were deposited during a 400 ky to 100 ky time span. Such shallow-water cycles, typical of many platforms, form only where shallow water intersects gently sloping substrates. The relative thicknesses of cycles (< 2 m to 15 m thick), magnitudes of relative sea-level fluctuations associated with each cycle (25-30 m), high rates of relative sea-level fluctuations (minimum of 25-120 cm/ky), and the widespread distribution of similar TCC cycles in the Mediterranean and elsewhere are supportive of a glacio-eustatic

Quantitative controls on location and architecture of carbonate depositional sequences: upper miocene, cabo de gata region, se Spain

USGS Publications Warehouse

Franseen, E.K.; Goldstein, R.H.; Farr, M.R.

1998-01-01

Sequence stratigraphy, pinning-point relative sea-level curves, and magnetostratigraphy provide the quantitative data necessary to understand how rates of sea-level change and different substrate paleoslopes are dominant controls on accumulation rate, carbonate depositional sequence location, and internal architecture. Five third-order (1-10 my) and fourth-order (0.1-1.0 my) upper Miocene carbonate depositional sequences (DS1A, DS1B, DS2, DS3, TCC) formed with superimposed higher-frequency sea-level cycles in an archipelago setting in SE Spain. Overall, our study indicates when areas of high substrate slope (> 15??) are in shallow water, independent of climate, the location and internal architecture of carbonate deposits are not directly linked to sea-level position but, instead, are controlled by location of gently sloping substrates and processes of bypass. In contrast, if carbonate sediments are generated where substrates of low slope ( 15.6 cm/ky to ??? 2 cm/ky and overall relative sea level rose at rates of 17-21.4 cm/ky. Higher frequency sea-level rates were about 111 to more than 260 cm/ky, producing onlapping, fining- (deepening-) upward cycles. Decreasing accumulation rates resulted from decreasing surface area for shallow-water sediment production, drowning of shallow-water substrates, and complex sediment dispersal related to the archipelago setting. Typical systems tract and parasequence development should not be expected in "bypass ramp" settings; facies of onlapping strata do not track base level and are likely to be significantly different compared to onlapping strata associated with coastal onlap. Basal and upper DS2 reef megabreccias (indicating the transition from cool to warmer climatic conditions) were eroded from steep upslope positions and redeposited downslope onto areas of gentle substrate during rapid sea-level falls (> 22.7 cm/ky) of short duration. Such rapid sea-level falls and presence of steep slopes are not conducive to formation of forced regressive systems tracts composed of downstepping reef clinoforms. The DS3 reefal platform formed where shallow water coincided with gently sloping substrates created by earlier deposition. Slow progradation (0.39-1.45 km/my) is best explained by the lack of an extensive bank top, progressively falling sea level, and low productivity resulting from siliciclastic debris and excess nutrients shed from nearby volcanic islands. Although DS3 strata were deposited during a third-order relative sea-level cycle, a typical transgresse??e systems tract is not recognizable, indicating that the initial relative rise in sea level was too rapid (??? 19 cm/ky). Downstepping reefs, forming a forced regressive systems tract, were deposited during the relative sea-level fall at the end of DS3, indicating that relatively slow rates of fall (10 cm/ky or less) over favorable paleoslope conditions are conducive to generation of forced regressive systems tracts consisting of downstepping reef clinoforms. The TCC sequence consists of four shallow -water sedimentary cycles that were deposited during a 400 ky to 100 ky time span. Such shallow-water cycles, typical of many platforms, form only where shallow water intersects gently sloping substrates. The relative thicknesses of cycles (< 2 m to 15 m thick), magnitudes of relative sea-level fluctuations associated with each cycle (25-30 m), high rates of relative sea-level fluctuations (minimum of 25-120 cm/ky), and the widespread distribution of similar TCC cycles in the Mediterranean and elsewhere are supportive of a glacio-eustati

Caves, Carbonates and Climate: Karst Landscape Development through Environmental Forcing, Little Cayman Island

NASA Astrophysics Data System (ADS)

Hsia, S.; Ouellette, G., Jr.; Manfrino, C.

2016-12-01

The Cayman Islands are situated in the west-central Caribbean Sea, between Cuba and the Yucatan Peninsula. Little Cayman Island (LCI) is relatively underdeveloped and understudied in comparison to its sister islands, Grand Cayman and Cayman Brac, and hosts less than 200 permanent residents over a 30 square kilometer area. However, like its sister islands, LCI is a small carbonate platform derived from reef building during the Oligocene, Miocene, and Quaternary. The shared geologic history of the Cayman Islands along with minimal human disturbance makes LCI an ideal site to study an island karst landscape. Conduction of field surveys, stratigraphic and petrologic comparisons between primary lithologic formations, and compilation of a geospatial inventory of karst features and lithology of LCI using GIS revealed novel insights into landscape evolution on LCI. In addition to surface karst surveys, several caves on the island were mapped. Cave morphologies suggest that evolution of LCI karst features have been driven by both hydroclimate, as well as salt and freshwater mixing, modulated by sea level fluctuations. These findings are mirrored in the lithology of partially dolomitized Miocene carbonates, which contain paleo-karst fill features and reveal hydroclimate influence, as well as enhanced resistance to dissolution in the present day, ostensibly from submersion in Mg-rich sea waters prior to the Quaternary. These findings shed light on the complex relationship of climate, geology, and karst landscape development on this particular carbonate island. This information is critical in anticipating structural and hydrogeological integrity on LCI under future climate change scenarios and serves as an example of the interplay linking climate and geologic processes to karst landscape development on small carbonate islands.

Linking Wave Forcing to Coral Cover and Structural Complexity Across Coral Reef Flats

NASA Astrophysics Data System (ADS)

Harris, D. L.; Rovere, A.; Parravicini, V.; Casella, E.

2015-12-01

The hydrodynamic regime is a significant component in the geomorphic and ecological development of coral reefs. The energy gradients and flow conditions generated by the breaking and transformation of waves across coral reef crests and flats drive changes in geomorphic structure, and coral growth form and distribution. One of the key aspects in regulating the wave energy propagating across reef flats is the rugosity or roughness of the benthic substrate. Rugosity and structural complexity of coral reefs is also a key indicator of species diversity, ecological functioning, and reef health. However, the links between reef rugosity, coral species distribution and abundance, and hydrodynamic forcing are poorly understood. In this study we examine this relationship by using high resolution measurement of waves in the surf zone and coral reef benthic structure.Pressure transducers (logging at 4 Hz) were deployed in cross reef transects at two sites (Tiahura and Ha'apiti reef systems) in Moorea, French Polynesia with wave characteristics determined on a wave by wave basis. A one dimensional hydrodynamic model (XBeach) was calibrated from this data to determine wave processes on the reef flats under average conditions. Transects of the reef benthic structure were conducted using photographic analysis and the three dimensional reef surface was constructed using structure from motion procedures. From this analysis reef rugosity, changes in coral genus and growth form, and across reef shifts in benthic community were determined. The results show clear changes in benthic assemblages along wave energy gradients with some indication of threshold values of wave induced bed shear stress above which live coral cover was reduced. Reef rugosity was shown to be significantly along the cross-reef transect which has important implications for accurate assessment of wave dissipation across coral reef flats. Links between reef rugosity and coral genus were also observed and may indicate that some coral species are crucial in maintaining the structural diversity of coral reefs.

Predicting climate-driven regime shifts versus rebound potential in coral reefs.

PubMed

Graham, Nicholas A J; Jennings, Simon; MacNeil, M Aaron; Mouillot, David; Wilson, Shaun K

2015-02-05

Climate-induced coral bleaching is among the greatest current threats to coral reefs, causing widespread loss of live coral cover. Conditions under which reefs bounce back from bleaching events or shift from coral to algal dominance are unknown, making it difficult to predict and plan for differing reef responses under climate change. Here we document and predict long-term reef responses to a major climate-induced coral bleaching event that caused unprecedented region-wide mortality of Indo-Pacific corals. Following loss of >90% live coral cover, 12 of 21 reefs recovered towards pre-disturbance live coral states, while nine reefs underwent regime shifts to fleshy macroalgae. Functional diversity of associated reef fish communities shifted substantially following bleaching, returning towards pre-disturbance structure on recovering reefs, while becoming progressively altered on regime shifting reefs. We identified threshold values for a range of factors that accurately predicted ecosystem response to the bleaching event. Recovery was favoured when reefs were structurally complex and in deeper water, when density of juvenile corals and herbivorous fishes was relatively high and when nutrient loads were low. Whether reefs were inside no-take marine reserves had no bearing on ecosystem trajectory. Although conditions governing regime shift or recovery dynamics were diverse, pre-disturbance quantification of simple factors such as structural complexity and water depth accurately predicted ecosystem trajectories. These findings foreshadow the likely divergent but predictable outcomes for reef ecosystems in response to climate change, thus guiding improved management and adaptation.

The Oligo-Miocene of Eil (NE Somalia): a prograding coral- Lepidocyclina system

NASA Astrophysics Data System (ADS)

Bosellini, A.; Russo, A.; Arush, M. A.; Cabdulqadir, M. M.

The Oligo-Miocene succession of Eil is the product of a depositional regression and constitutes a 120-150 m thick depositional sequence that prograded seaward for at least 20-25 km. Its time-transgressive stratigraphy is documented physically by well exposed tangential clinoforms (previously considered as evidence of a tectonic coastal flexure) and biostratigraphically by the occurrence of calcareous nannoplankton, planktonic and benthonic foraminifera, and a rich coral fauna. The upper boundary of the sequence is indicated by a reefal toplap, which constitutes the flat surface of the Nogal Plateau. Age (Chattian to Burdigalian) and toplap relationships of the sequence indicate clearly that progradation took place after the Late Oligocene flooding which followed the strong fall of sea-level during the Chattian. Because of the horizontal geometry of the entire sedimentary system, it has been possible to make a clear environmental reconstruction and a facies model with original water depths. A worldwide Tertiary facies—the Lepidocyclina beds— was confined to the front of the reef, at depths ranging from 35-40 to 120-130 m.

Spatial Patterns in Herbivory on a Coral Reef Are Influenced by Structural Complexity but Not by Algal Traits

PubMed Central

Vergés, Adriana; Vanderklift, Mathew A.; Doropoulos, Christopher; Hyndes, Glenn A.

2011-01-01

Background Patterns of herbivory can alter the spatial structure of ecosystems, with important consequences for ecosystem functions and biodiversity. While the factors that drive spatial patterns in herbivory in terrestrial systems are well established, comparatively less is known about what influences the distribution of herbivory in coral reefs. Methodology and Principal Findings We quantified spatial patterns of macroalgal consumption in a cross-section of Ningaloo Reef (Western Australia). We used a combination of descriptive and experimental approaches to assess the influence of multiple macroalgal traits and structural complexity in establishing the observed spatial patterns in macroalgal herbivory, and to identify potential feedback mechanisms between herbivory and macroalgal nutritional quality. Spatial patterns in macroalgal consumption were best explained by differences in structural complexity among habitats. The biomass of herbivorous fish, and rates of herbivory were always greater in the structurally-complex coral-dominated outer reef and reef flat habitats, which were also characterised by high biomass of herbivorous fish, low cover and biomass of macroalgae and the presence of unpalatable algae species. Macroalgal consumption decreased to undetectable levels within 75 m of structurally-complex reef habitat, and algae were most abundant in the structurally-simple lagoon habitats, which were also characterised by the presence of the most palatable algae species. In contrast to terrestrial ecosystems, herbivory patterns were not influenced by the distribution, productivity or nutritional quality of resources (macroalgae), and we found no evidence of a positive feedback between macroalgal consumption and the nitrogen content of algae. Significance This study highlights the importance of seascape-scale patterns in structural complexity in determining spatial patterns of macroalgal consumption by fish. Given the importance of herbivory in maintaining the ability of coral reefs to reorganise and retain ecosystem functions following disturbance, structural complexity emerges as a critical feature that is essential for the healthy functioning of these ecosystems. PMID:21347254

Benthic foraminifera baseline assemblages from a coastal nearshore reef complex on the central Great Barrier Reef

NASA Astrophysics Data System (ADS)

Johnson, Jamie; Perry, Chris; Smithers, Scott; Morgan, Kyle

2016-04-01

Declining water quality due to river catchment modification since European settlement (c. 1850 A.D.) represents a major threat to the health of coral reefs on Australia's Great Barrier Reef (GBR), particularly for those located in the coastal waters of the GBR's inner-shelf. These nearshore reefs are widely perceived to be most susceptible to declining water quality owing to their close proximity to river point sources. Despite this, nearshore reefs have been relatively poorly studied with the impacts and magnitudes of environmental degradation still remaining unclear. This is largely due to ongoing debates concerning the significance of increased sediment yields against naturally high background sedimentary regimes. Benthic foraminifera are increasingly used as tools for monitoring environmental and ecological change on coral reefs. On the GBR, the majority of studies have focussed on the spatial distributions of contemporary benthic foraminiferal assemblages. While baseline assemblages from other environments (e.g. inshore reefs and mangroves) have been described, very few records exist for nearshore reefs. Here, we present preliminary results from the first palaeoecological study of foraminiferal assemblages of nearshore reefs on the central GBR. Cores were recovered from the nearshore reef complex at Paluma Shoals using percussion techniques. Recovery was 100%, capturing the entire Holocene reef sequence of the selected reef structures. Radiocarbon dating and subsequent age-depth modelling techniques were used to identify reef sequences pre-dating European settlement. Benthic foraminifera assemblages were reconstructed from the identified sequences to establish pre-European ecological baselines with the aim of providing a record of foraminiferal distribution during vertical reef accretion and against which contemporary ecological change may be assessed.

Comparison of Commercial Structure-From Photogrammety Software Used for Underwater Three-Dimensional Modeling of Coral Reef Environments

NASA Astrophysics Data System (ADS)

Burns, J. H. R.; Delparte, D.

2017-02-01

Structural complexity in ecosystems creates an assortment of microhabitat types and has been shown to support greater diversity and abundance of associated organisms. The 3D structure of an environment also directly affects important ecological parameters such as habitat provisioning and light availability and can therefore strongly influence ecosystem function. Coral reefs are architecturally complex 3D habitats, whose structure is intrinsically linked to the ecosystem biodiversity, productivity, and function. The field of coral ecology has, however, been primarily limited to using 2-dimensional (2D) planar survey techniques for studying the physical structure of reefs. This conventional approach fails to capture or quantify the intricate structural complexity of corals that influences habitat facilitation and biodiversity. A 3-dimensional (3D) approach can obtain accurate measurements of architectural complexity, topography, rugosity, volume, and other structural characteristics that affect biodiversity and abundance of reef organisms. Structurefrom- Motion (SfM) photogrammetry is an emerging computer vision technology that provides a simple and cost-effective method for 3D reconstruction of natural environments. SfM has been used in several studies to investigate the relationship between habitat complexity and ecological processes in coral reef ecosystems. This study compared two commercial SfM software packages, Agisoft Photoscan Pro and Pix4Dmapper Pro 3.1, in order to assess the cpaability and spatial accuracy of these programs for conducting 3D modeling of coral reef habitats at three spatial scales.

Quaternary onset and evolution of Kimberley coral reefs (Northwest Australia) revealed by high-resolution seismic imaging

NASA Astrophysics Data System (ADS)

Bufarale, Giada; Collins, Lindsay B.; O'Leary, Michael J.; Stevens, Alexandra; Kordi, Moataz; Solihuddin, Tubagus

2016-07-01

The inner shelf Kimberley Bioregion of Northwest Australia is characterised by a macrotidal setting where prolific coral reefs growth as developed around a complex drowned landscape and is considered a biodiversity "hotspot". High-resolution shallow seismic studies were conducted across various reef settings in the Kimberley (Buccaneer Archipelago, north of Dampier Peninsula, latitude: between 16°40‧S and 16°00‧S) to evaluate stratigraphic evolution, interaction with different substrates, morphological patterns and distribution. Reef sites were chosen to assess most of the reef types present, particularly high intertidal planar reefs and fringing reefs. Reef internal acoustic reflectors were identified according to their shape, stratigraphic position and characteristics. Two main seismic horizons were identified marking the boundaries between Holocene reef (Marine Isotope Stage 1, MIS 1, last 12 ky), commonly 10-20 m thick, and MIS 5 (Last Interglacial, LIG, ~120 ky, up to 12 m thick) and Proterozoic rock foundation over which Quaternary reef growth occurred. Within the Holocene Reef unit, at least three minor internal reflectors, generally discontinuous, subparallel to the reef flat were recognised and interpreted as either growth hiatuses or a change of the coral framework or sediment matrix. The LIG reefs represent a new northernmost occurrence along the Western Australian coast. The research presented here achieved the first regional geophysical study of the Kimberley reefs. Subbottom profiles demonstrated that the surveyed reefs are characterised by a multi-stage reef buildup, indicating that coral growth occurred in the Kimberley during previous sea level highstands. The data show also that antecedent substrate and regional subsidence have contributed, too, in determining the amount of accommodation available for reef growth and controlling the morphology of the successive reef building stages. Moreover, the study showed that in spite of macrotidal conditions, high-turbidity and frequent high-energy cyclonic events, corals have exhibited prolific reef growth during the Holocene developing significant reef accretionary structures. As a result coral reefs have generating habitat complexity and species diversity in what is a biodiversity hotspot.

Multi-site evaluation of IKONOS data for classification of tropical coral reef environments

USGS Publications Warehouse

Andrefouet, S.; Kramer, Philip; Torres-Pulliza, D.; Joyce, K.E.; Hochberg, E.J.; Garza-Perez, R.; Mumby, P.J.; Riegl, Bernhard; Yamano, H.; White, W.H.; Zubia, M.; Brock, J.C.; Phinn, S.R.; Naseer, A.; Hatcher, B.G.; Muller-Karger, F. E.

2003-01-01

Ten IKONOS images of different coral reef sites distributed around the world were processed to assess the potential of 4-m resolution multispectral data for coral reef habitat mapping. Complexity of reef environments, established by field observation, ranged from 3 to 15 classes of benthic habitats containing various combinations of sediments, carbonate pavement, seagrass, algae, and corals in different geomorphologic zones (forereef, lagoon, patch reef, reef flats). Processing included corrections for sea surface roughness and bathymetry, unsupervised or supervised classification, and accuracy assessment based on ground-truth data. IKONOS classification results were compared with classified Landsat 7 imagery for simple to moderate complexity of reef habitats (5-11 classes). For both sensors, overall accuracies of the classifications show a general linear trend of decreasing accuracy with increasing habitat complexity. The IKONOS sensor performed better, with a 15-20% improvement in accuracy compared to Landsat. For IKONOS, overall accuracy was 77% for 4-5 classes, 71% for 7-8 classes, 65% in 9-11 classes, and 53% for more than 13 classes. The Landsat classification accuracy was systematically lower, with an average of 56% for 5-10 classes. Within this general trend, inter-site comparisons and specificities demonstrate the benefits of different approaches. Pre-segmentation of the different geomorphologic zones and depth correction provided different advantages in different environments. Our results help guide scientists and managers in applying IKONOS-class data for coral reef mapping applications. ?? 2003 Elsevier Inc. All rights reserved.

Geological evolution of the Iraqi Mesopotamia Foredeep, inner platform and near surroundings of the Arabian Plate

NASA Astrophysics Data System (ADS)

Sissakian, Varoujan K.

2013-08-01

The Iraqi territory could be divided into four main tectonic zones; each one has its own characteristics concerning type of the rocks, their age, thickness and structural evolution. These four zones are: (1) Inner Platform (stable shelf), (2) Outer Platform (unstable shelf), (3) Shalair Zone (Terrain), and (4) Zagros Suture Zone. The first two zones of the Arabian Plate lack any kind of metamorphism and volcanism. The Iraqi territory is located in the extreme northeastern part of the Arabian Plate, which is colliding with the Eurasian (Iranian) Plate. This collision has developed a foreland basin that includes: (1) Imbricate Zone, (2) High Folded Zone, (3) Low Folded Zone and (4) Mesopotamia Foredeep. The Mesopotamia Foredeep, in Iraq includes the Mesopotamia Plain and the Jazira Plain; it is less tectonically disturbed as compared to the Imbricate, High Folded and Low Folded Zones. Quaternary alluvial sediments of the Tigris and Euphrates Rivers and their tributaries as well as distributaries cover the central and southeastern parts of the Foredeep totally; it is called the Mesopotamian Flood Plain. The extension of the Mesopotamia Plain towards northwest however, is called the Jazira Plain, which is covered by Miocene rocks. The Mesopotamia Foredeep is represented by thick sedimentary sequence, which thickens northwestwards including synrift sediments; especially of Late Cretaceous age, whereas on surface the Quaternary sediments thicken southeastwards. The depth of the basement also changes from 8 km, in the west to 14 km, in the Iraqi-Iranian boarders towards southeast. The anticlinal structures have N-S trend, in the extreme southern part of the Mesopotamia Foredeep and extends northwards until the Latitude 32°N, within the Jazira Plain, there they change their trends to NW-SE, and then to E-W trend. The Mesozoic sequence is almost without any significant break, with increase in thickness from the west to the east, attaining 5 km. The sequence forms the main source and reservoir rocks in the central and southern parts of Iraq. The Cenozoic sequence consists of Paleogene open marine carbonates, which grades upwards into Neogene lagoonal marine; of Early Miocene and evaporitic rocks; of Middle Miocene age, followed by thick molasses of continental clastics that attain 3500 m in thickness; starting from Late Miocene. The Quaternary sediments are very well developed in the Mesopotamia Plain and they thicken southwards to reach about 180 m near Basra city; in the extreme southeastern part of Iraq. The Iraqi Inner Platform (stable shelf) is a part of the Arabian Plate, being less affected by tectonic disturbances; it covers the area due to south and west of the Euphrates River. The main tectonic feature in this zone that had affected on the geology of the area is the Rutbah Uplift; with less extent is the Ga'ara High. The oldest exposed rocks within the Inner Platform belong to Ga'ara Formation of Permian age; it is exposed only in the Ga'ara Depression. The Permian rocks are overlain by Late Triassic rocks; represented by Mulussa and Zor Hauran formations, both of marine carbonates with marl intercalations. The whole Triassic rocks are absent west, north and east of Ga'ara Depression. Jurassic rocks, represented by five sedimentary cycles, overlie the Triassic rocks. Each cycle consists of clastic rocks overlain by carbonates, being all of marine sediments; whereas the last one (Late Jurassic) consists of marine carbonates only. All the five formations are separated from each other by unconformable contacts. Cretaceous rocks, represented by seven sedimentary cycles, overlie the Jurassic rocks. Marine clastics overlain by marine carbonates. Followed upwards (Late Cretaceous) by continental clastics overlain by marine carbonates; then followed by marine carbonates with marl intercalations, and finally by marine clastics overlain by carbonates; representing the last three cycles, respectively. The Paleocene rocks form narrow belt west of the Ga'ara Depression, represented by Early-Late Paleocene phosphatic facies, which is well developed east of Rutbah Uplift and extends eastwards in the Foredeep. Eocene rocks; west of Rutbah Uplift are represented by marine carbonates that has wide aerial coverage in south Iraq. Locally, east of Rutbah Uplift unconformable contacts are recorded between Early, Middle and Late Eocene rocks. During Oligocene, in the eastern margin of the Inner Platform, the Outer Platform was uplifted causing very narrow depositional Oligocene basin. Therefore, very restricted exposures are present in the northern part of the Inner Platform (north of Ga'ara Depression), represented by reef, forereef sediments of some Oligocene formations. The Miocene rocks have no exposures west of Rutbah Uplift, but north and northwestwards are widely exposed represented by Early Miocene of marine carbonates with marl intercalations. Very locally, Early Miocene deltaic clastics and carbonates, are interfingering with the marine carbonates. The last marine open sea sediments, locally with reef, represent the Middle Miocene rocks and fore reef facies that interfingers with evaporates along the northern part of Abu Jir Fault Zone, which is believed to be the reason for the restriction of the closed lagoons; in the area. During Late Miocene, the continental phase started in Iraq due to the closure of the Neo-Tethys and collision of the Sanandaj Zone with the Arabian Plate. The continental sediments consist of fine clastics. The Late Miocene - Middle Pliocene sediments were not deposited in the Inner Platform. The Pliocene-Pleistocene sediments are represented by cyclic sediments of conglomeratic sandstone overlain by fresh water limestone, and by pebbly sandstone. The Quaternary sediments are poorly developed in the Inner Platform. Terraces of Euphrates River and those of main valleys represent pleistocene sediments. Flood plain of the Euphrates River and those of large valleys represent Holocene sediments. Residual soil is developed, widely in the western part of Iraq, within the western marginal part of the Inner Platform.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, R.W.; Fernandez-Mendiola, P.A.; Gili, E.

During the Early Cretaceous, coral-algal communities occupied deeper water habitats in the reef ecosystem, and rudist communities generally populated the shallow-water, carbonate-sand substrates. During the middle Cretaceous, however, coral-algal communities became less common, and Late Cretaceous reef communities consisted of both rudist-dominated and rudist-coral communities. In the Pyrenean basins and other basins in the Mediterranean, coral associations co-existed with rudists forming complex buildups at the shelf-edge. In some parts of these buildups corals were nearly as abundant as rudists; in some complex buildups large coral colonies encrusted the rudists. Behind the shelf margin cylindrical, elevator rudists dominated the lenticular thicketsmore » that were interspersed with carbonate sands. Global changes in oceanic conditions, such as marine productivity and oxygen content, may have stressed the deeper coral-algal reef communities leaving rudists as the major shallow reef biota in Caribbean reefs. However, the co-occurrence of corals with rudists in these Pyrenean complex buildups suggests that corals were able to compete with rudists for resources. The corals in the complex buildups generally belong to genera different from those in the coral-algal communities. Perhaps this ecological stress in the mid-Cretaceous resulted in the evolution of new coral taxa.« less

Contrasting evolutionary patterns in two reef-corals and their possible relationship to life history traits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, A.B.

1985-01-01

Multivariate statistical analyses have been used to redefine species within two genera of reef-corals (Porites and Montastraea) and to trace their evolutionary patterns through a continuous sequence from late Miocene to early Pliocene time. The material studied consists of populations sampled at regular intervals through four stratigraphic sections in the northern Dominican Republic. The results show that species in the first genus (Porites) have relatively short durations, morphologic stability, and narrow spatial distributions. Their overall evolutionary history is characterized by short periods of radiation and widespread extinction, separated by longer periods of stasis. In contrast, species in the second genusmore » (Montastraea) exhibit various different durations and distributions and directional morphologic trends. These differences in patterns may be related to the dissimilar life histories of the two genera. Patterns in the first genus appear more common in organisms having high larval recruitment, high mortality, high genetic variation, and less morphologic distance between species. Patterns in the second genus occur more frequently in slower growing, phenotypically plastic organisms experiencing less recruitment and mortality and showing more morphologic distance between species.« less

The identification of Oligo-Miocene mammalian palaeocommunities from the Riversleigh World Heritage Area, Australia and an appraisal of palaeoecological techniques

PubMed Central

Black, Karen H.; Archer, Michael; Hand, Suzanne J.

2017-01-01

Fourteen of the best sampled Oligo-Miocene local faunas from the Riversleigh World Heritage Area, north-western Queensland, Australia are analysed using classification and ordination techniques to identify potential mammalian palaeocommunities and palaeocommunity types. Abundance data for these faunas are used, for the first time, in conjunction with presence/absence data. An early Miocene Faunal Zone B and two middle Miocene Faunal Zone C palaeocommunities are recognised, as well as one palaeocommunity type. Change in palaeocommunity structure, between the early Miocene and middle Miocene, may be the result of significant climate change during the Miocene Carbon Isotope Excursion. The complexes of local faunas identified will allow researchers to use novel palaeocommunities in future analyses of Riversleigh’s fossil faunas. The utility of some palaeoecological multivariate indices and techniques is examined. The Dice index is found to outperform other binary similarity/distance coefficients, while the UPGMA algorithm is more useful than neighbour joining. Evidence is equivocal for the usefulness of presence/absence data compared to abundance. PMID:28674663

A macroecological glance at the structure of late Miocene rodent assemblages from Southwest Europe

PubMed Central

Cano, Ana Rosa Gómez; Cantalapiedra, Juan L.; Álvarez-Sierra, M. Ángeles; Fernández, Manuel Hernández

2014-01-01

Deep-time perspectives in macroecology are essential with regard to understanding the impact of climate forcing on faunal communities. Using late Miocene rodent faunas (12 to 5 Ma) from two different biogeographical provinces from southwestern Europe, we asked whether the waxing and waning of faunas with dissimilar ecological affinities tracked climate in different ways. The latest middle Miocene featured a fauna dominated by dormice with forest and mixed-habitat affinities. This group declined towards the Upper Miocene. Rodent taxa with the highest values of richness at the beginning of the Upper Miocene are generalists in the southern province and specialists of forested habitats in the northern province. Finally, we identified a third, increasingly significant group of rodents linked to open landscapes towards the end of the Miocene. These three broad ecological groups showed differential responses to a complex set of interconnected circumstances, including the biogeographic structure of the study area and climatic changes throughout time. PMID:25297009

A macroecological glance at the structure of late Miocene rodent assemblages from Southwest Europe.

PubMed

Gómez Cano, Ana Rosa; Cantalapiedra, Juan L; Álvarez-Sierra, M Ángeles; Hernández Fernández, Manuel

2014-10-09

Deep-time perspectives in macroecology are essential with regard to understanding the impact of climate forcing on faunal communities. Using late Miocene rodent faunas (12 to 5 Ma) from two different biogeographical provinces from southwestern Europe, we asked whether the waxing and waning of faunas with dissimilar ecological affinities tracked climate in different ways. The latest middle Miocene featured a fauna dominated by dormice with forest and mixed-habitat affinities. This group declined towards the Upper Miocene. Rodent taxa with the highest values of richness at the beginning of the Upper Miocene are generalists in the southern province and specialists of forested habitats in the northern province. Finally, we identified a third, increasingly significant group of rodents linked to open landscapes towards the end of the Miocene. These three broad ecological groups showed differential responses to a complex set of interconnected circumstances, including the biogeographic structure of the study area and climatic changes throughout time.

A macroecological glance at the structure of late Miocene rodent assemblages from Southwest Europe

NASA Astrophysics Data System (ADS)

Cano, Ana Rosa Gómez; Cantalapiedra, Juan L.; Álvarez-Sierra, M. Ángeles; Fernández, Manuel Hernández

2014-10-01

Deep-time perspectives in macroecology are essential with regard to understanding the impact of climate forcing on faunal communities. Using late Miocene rodent faunas (12 to 5 Ma) from two different biogeographical provinces from southwestern Europe, we asked whether the waxing and waning of faunas with dissimilar ecological affinities tracked climate in different ways. The latest middle Miocene featured a fauna dominated by dormice with forest and mixed-habitat affinities. This group declined towards the Upper Miocene. Rodent taxa with the highest values of richness at the beginning of the Upper Miocene are generalists in the southern province and specialists of forested habitats in the northern province. Finally, we identified a third, increasingly significant group of rodents linked to open landscapes towards the end of the Miocene. These three broad ecological groups showed differential responses to a complex set of interconnected circumstances, including the biogeographic structure of the study area and climatic changes throughout time.

Coral calcification and reef development under natural disturbances

NASA Astrophysics Data System (ADS)

Wall, M.; Schmidt, G. M.; Khokkiatiwong, S.; Richter, C.

2012-04-01

Corals are impressive ecosystem engineers shaping and influencing tropical shallow water environments through their complex carbonate framework. Calcification a key physiological process determining coral growth and reef development, is highly dependent on constant environmental conditions, especially temperature, aragonite saturation and pH. However, not in all reef areas such constant and stable conditons can be found. Coral reefs located in the Andaman Sea off the western Thai coast are subjected to large amplitude internal waves (LAIW), which induce strong oscillations in several physical and chemical environmental parameters and hence, offer the possibility to study the influence of fluctuating conditions on coral reefs. Characteristics of these oscillations as well as reef framework development have been studied on reefs of five islands, which are exposed to LAIW along their western sides and LAIW-sheltered on their eastern sides. LAIW reach these shallow water reef areas all year round, however, strongest fluctuations were recorded during the dry season (November to May) with temperature drops of up to 8°C and pH values ranging from 8.22-7.90. Several (up to 12) sudden changes in environmental conditions can occur during a day, which differ in intensity and duration. Salinity, pH and oxygen are well correlated with changes in temperature and thus, temperature variability calculated as degree days cooling (DDC) was used as proxy for the complex set of environmental variability. This proxy enabled us to combine frequency and intensity of disturbances in one value and allowed for ranking each study location according to the severity of LAIW disturbances. Framework height was found to be clearly reduced in areas exposed to LAIW compared to the complex three-dimensional carbonate framework in the LAIW-sheltered reefs. Moreover, it showed a strong linear correlation with DDC (Rsqr=0.732, p=0.007) indicating the negative effect of pulsed disturbances on coral reef development. LAIW are a ubiquitous phenomenon especially in tropical oceans where coral communities exposed to these internal waves may offer a unique possibility to study in situ the effect of several cumulative stressors on coral- and reef development, as well as the consequences for the whole reef community.

Warm-water coral reefs and climate change

NASA Astrophysics Data System (ADS)

Spalding, Mark D.; Brown, Barbara E.

2015-11-01

Coral reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent bleaching events that can lead to the loss of both coral cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of coral reefs is increasingly bleak.

The role of peripheral endemism and habitat associations in the evolution of the Indo-West Pacific tuskfishes (Labridae: Choerodon).

PubMed

Puckridge, Melody; Last, Peter R; Andreakis, Nikos

2015-03-01

The unrivalled level of biodiversity across the tropical Indo-Australian Archipelago (IAA) has been the subject of wide debate. Attempts to understand its origins have focussed on the timing of speciation, rates of diversification and the directionality of colonisation across geographical and climatic gradients in an array of marine groups. We investigate origins and evolution in the Choerodon tuskfishes, a group of labrids whose centre of diversity coincides with this region. Mitochondrial (COI, 16S) and nuclear (RAG2, Tmo4c4) molecular phylogenies and biogeographic analyses, coupled with molecular clock dating, were inferred from 19 of the 23 valid Choerodon species. Two additional, undescribed Choerodon species were also included, showing reciprocal monophyly in both genomes, confirming their species level status. Choerodon diverged from their ancestral sister group, the Odacines, at the onset of the Miocene, coinciding with the collision of the Australian and Eurasian Plates when extensive areas of shallow-water habitat formed. Despite subsequent evolutionary patterns being partially obscured by overlapping distribution ranges between many species and a lack of clear evidence for climatically driven lineage divergences, our data support an evolutionary scenario of peripheral endemics budding from once widespread populations across this biodiversity hotspot. Interestingly, these peripheral endemics tend to occupy more specialised reef or non-reef habitats whereas widespread groups appear to generally take advantage of both reef and non-reef environments. Our results are discussed in light of the most accredited hypotheses proposed to explain species richness in the IAA, with some support for processes such as centrifugal speciation. Copyright © 2014 Elsevier Inc. All rights reserved.

Miocene to Recent geological evolution of the Lazufre segment in the Andean volcanic arc

NASA Astrophysics Data System (ADS)

Naranjo, J. A.; Villa, V.; Ramírez, C.; Pérez de Arce, C.

2014-12-01

The volcano-tectonic setting in which the InSAR-detected Lazufre deformation is developing is particularly relevant in the evolution of this Andean volcanic arc segment (25-26°S). Through regional mapping techniques, a comprehensive field control in addition to geochronological sampling, various volcanic units comprising stratovolcanoes, volcanic complexes, ignimbrites and caldera structures are distinguished. The Lazufre intumescence is located above the overlying block of the NE trending Middle Miocene, Pedernales-Arizaro overthrust. This area comprises an Upper Miocene (8-4 Ma) basal unit of andesitic-dacitic volcanoes and lava fields, upon which nine volcanic complexes of similar composition, including Caletones de Cori Ignimbrite and Escorial Volcano, Lastarria, Cordón del Azufre and Bayo volcanic complexes, were emplaced in several pulses between 3.5 Ma and Holocene times. Coalescing Lazufre structure, immediately to the SE, we have discovered the Miocene (9.8 Ma) Los Colorados caldera. This caldera is 30 km in diameter and sourced the homonymous dacitic ignimbrite of about 500 km3. The caldera scarp was formed in Paleozoic rocks, Miocene dacitic-rhyolitic ignimbrites and ~16 and 10 Ma volcanoes. A 6.9-6.8 Ma andesitic-dacitic volcano ridge formed by Abra Grande, Río Grande and Aguas Calientes stratovolcanoes, from NE to SW, is nested on the caldera floor. Lavas of early stages of Cordón del Azufre and Bayo complexes were shed into the NW part of the caldera. The coalescing structure formed by the Lazufre intumescence and Los Colorados caldera is conjugate at about 30° to the Pedernales-Arizaro overthrust, and has a NW-SE orientation, parallel to the Archibarca lineament. A SE to NW migration of volcanism is observed along this structure at least since the Middle Miocene. We proposed that, since Miocene, tectonic spaces with no surficial fault displacements and conjugated to the main compressive structures within the upper crust, have been created as a result of tensional stresses. Subsequently, the so increased lithostatic gradient could play a major role in the vertical traction of magma rising, favoring crustal assimilation processes. The available geochronological data indicate that the deformation that preceded the Los Colorados caldera occurred in a maximum period between 13 and 10 Ma.

Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef

PubMed Central

Valdivia, Abel; Cox, Courtney E.; Silbiger, Nyssa J.; Bruno, John F.

2017-01-01

Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0–10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations. PMID:28560093

Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef.

PubMed

Hackerott, Serena; Valdivia, Abel; Cox, Courtney E; Silbiger, Nyssa J; Bruno, John F

2017-01-01

Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0-10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

A Synthesis and Comparison of Approaches for Quantifying Coral Reef Structure

NASA Astrophysics Data System (ADS)

Duvall, M. S.; Hench, J. L.

2016-02-01

The complex physical structures of coral reefs provide substrate for benthic organisms, surface area for material fluxes, and have been used as a predictor of reef-fish biomass and biodiversity. Coral reef topography has a first order effect on reef hydrodynamics by imposing drag forces and increasing momentum and scalar dispersion. Despite its importance, quantifying reef topography remains a challenge, as it is patchy and discontinuous while also varying over orders of magnitude in spatial scale. Previous studies have quantified reef structure using a range of 1D and 2D metrics that estimate vertical roughness, which is the departure from a flat geometric profile or surface. However, there is no general mathematical or conceptual framework by which to apply or compare these roughness metrics. While the specific calculations of different metrics vary, we propose that they can be classified into four categories based on: 1) vertical relief relative to a reference height; 2) gradients in vertical relief; 3) surface contour distance; or 4) variations in roughness with scale. We apply metrics from these four classes to idealized reef topography as well as natural reef topography data from Moorea, French Polynesia. Through the use of idealized profiles, we demonstrate the potential for reefs with different morphologies to possess the same value for some scale-dependent metrics (i.e. classes 1-3). Due to the superposition of variable-scale roughness elements in reef topography, we find that multi-scale metrics (i.e. class 4) can better characterize structural complexity by capturing surface roughness across a range of spatial scales. In particular, we provide evidence of the ability of 1D continuous wavelet transforms to detect changes in dominant roughness scales on idealized topography as well as within real reef systems.

75 FR 2158 - Palmyra Atoll National Wildlife Refuge, U.S. Pacific Island Territory

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-14

... migratory birds, coral reefs, and threatened and endangered species in their natural setting. Palmyra Atoll..., (808) 792-9586. U.S. Mail: Beth Flint, Acting Project Leader, Pacific Reefs National Wildlife Refuge..., Pacific Reefs National Wildlife Refuge Complex, phone (808) 792-9553. SUPPLEMENTARY INFORMATION: Refuge...

Intimate Views of Cretaceous Plutons, the Colorado River Extensional Corridor, and Colorado River Stratigraphy in and near Topock Gorge, Southwest USA

NASA Astrophysics Data System (ADS)

Howard, K. A.; John, B. E.; Nielson, J. E.; Miller, J. M.; Priest, S. S.

2010-12-01

Geologic mapping of the Topock 7.5’ quadrangle, CA-AZ, reveals a structurally complex part of the Colorado River extensional corridor, and a younger stratigraphic record of landscape evolution during the history of the Colorado River. Paleoproterozoic gneisses and Mesoproterozoic granitoids and diabase sheets are exposed through cross-sectional thicknesses of many kilometers. Mesozoic to Tertary igneous rocks intrude the older rocks and include dismembered parts of the Late Cretaceous Chemehuevi Mountains Plutonic Suite. Plutons of this suite exposed in the Arizona part of the quad reconstruct, if Miocene deformation is restored, as cupolas capping the sill-like Chemehuevi Mountains batholith exposed in California. A nonconformity between Proterozoic and Miocene rocks reflects pre-Miocene uplift and erosional stripping of regional Paleozoic and Mesozoic strata. Thick (1-3 km) Miocene sections of volcanic rocks, sedimentary breccias, and conglomerate record the Colorado River extensional corridor’s structural and erosional evolution. Four major Miocene low-angle normal faults and a steep block-bounding Miocene fault divide the deformed rocks into major structural plates and giant tilted blocks on the east side of the Chemehuevi Mountains core complex. The low-angle faults attenuate >10 km of crustal section, superposing supracrustal and upper crustal rocks against originally deeper gneisses and granitoids. The block-bounding Gold Dome fault zone juxtaposes two large hanging-wall blocks, each tilted 90°, and splays at its tip into folds that deform layered Miocene rocks. A 15-16 Ma synfaulting intrusion occupies the triangular zone or gap where the folding strata detached from an inside corner along this fault between the tilt blocks. Post-extensional landscape evolution is recorded by upper Miocene to Quaternary strata, locally deformed. This includes several Pliocene and younger aggradational episodes in the Colorado River valley, and intervening degradation episodes at times when the river re-incised. Post-Miocene aggradational sequences include (1) the Bouse Formation, (2) fluvial deposits correlated with the alluvium of Bullhead City, (3) a younger fluvial boulder conglomerate, (4) the Chemehuevi Formation and related valley-margin deposits, and (5) and Holocene deposits under the valley floor.

Warm-water coral reefs and climate change.

PubMed

Spalding, Mark D; Brown, Barbara E

2015-11-13

Coral reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent bleaching events that can lead to the loss of both coral cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of coral reefs is increasingly bleak. Copyright © 2015, American Association for the Advancement of Science.

Artificial breakwaters as garbage bins: Structural complexity enhances anthropogenic litter accumulation in marine intertidal habitats.

PubMed

Aguilera, Moisés A; Broitman, Bernardo R; Thiel, Martin

2016-07-01

Coastal urban infrastructures are proliferating across the world, but knowledge about their emergent impacts is still limited. Here, we provide evidence that urban artificial reefs have a high potential to accumulate the diverse forms of litter originating from anthropogenic activities around cities. We test the hypothesis that the structural complexity of urban breakwaters, when compared with adjacent natural rocky intertidal habitats, is a driver of anthropogenic litter accumulation. We determined litter abundances at seven sites (cities) and estimated the structural complexity in both urban breakwaters and adjacent natural habitats from northern to central Chile, spanning a latitudinal gradient of ∼15° (18°S to 33°S). Anthropogenic litter density was significantly higher in coastal breakwaters when compared to natural habitats (∼15.1 items m(-2) on artificial reefs versus 7.4 items m(-2) in natural habitats) at all study sites, a pattern that was temporally persistent. Different litter categories were more abundant on the artificial reefs than in natural habitats, with local human population density and breakwater extension contributing to increase the probabilities of litter occurrence by ∼10%. In addition, structural complexity was about two-fold higher on artificial reefs, with anthropogenic litter density being highest at intermediate levels of structural complexity. Therefore, the spatial structure characteristic of artificial reefs seems to enhance anthropogenic litter accumulation, also leading to higher residence time and degradation potential. Our study highlights the interaction between coastal urban habitat modification by establishment of artificial reefs, and pollution. This emergent phenomenon is an important issue to be considered in future management plans and the engineering of coastal ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

New constraints on the spatial distribution and morphology of the Halimeda bioherms of the Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

McNeil, Mardi A.; Webster, Jody M.; Beaman, Robin J.; Graham, Trevor L.

2016-12-01

Halimeda bioherms occur as extensive geological structures on the northern Great Barrier Reef (GBR), Australia. We present the most complete, high-resolution spatial mapping of the northern GBR Halimeda bioherms, based on new airborne lidar and multibeam echosounder bathymetry data. Our analysis reveals that bioherm morphology does not conform to the previous model of parallel ridges and troughs, but is far more complex than previously thought. We define and describe three morphological sub-types: reticulate, annulate, and undulate, which are distributed in a cross-shelf pattern of reduced complexity from east to west. The northern GBR bioherms cover an area of 6095 km2, three times larger than the original estimate, exceeding the area and volume of calcium carbonate in the adjacent modern shelf-edge barrier reefs. We have mapped a 1740 km2 bioherm complex north of Raine Island in the Cape York region not previously recorded, extending the northern limit by more than 1° of latitude. Bioherm formation and distribution are controlled by a complex interaction of outer-shelf geometry, regional and local currents, coupled with the morphology and depth of continental slope submarine canyons determining the delivery of cool, nutrient-rich water upwelling through inter-reef passages. Distribution and mapping of Halimeda bioherms in relation to Great Barrier Reef Marine Park Authority bioregion classifications and management zones are inconsistent and currently poorly defined due to a lack of high-resolution data not available until now. These new estimates of bioherm spatial distribution and morphology have implications for understanding the role these geological features play as structurally complex and productive inter-reef habitats, and as calcium carbonate sinks which record a complete history of the Holocene post-glacial marine transgression in the northern GBR.

Deep under the sea: unraveling the evolutionary history of the deep-sea squat lobster Paramunida (Decapoda, Munididae).

PubMed

Cabezas, Patricia; Sanmartín, Isabel; Paulay, Gustav; Macpherson, Enrique; Machordom, Annie

2012-06-01

The diversification of Indo-Pacific marine fauna has long captivated the attention of evolutionary biologists. Previous studies have mainly focused on coral reef or shallow water-associated taxa. Here, we present the first attempt to reconstruct the evolutionary history--phylogeny, diversification, and biogeography--of a deep-water lineage. We sequenced the molecular markers 16S, COI, ND1, 18S, and 28S for nearly 80% of the nominal species of the squat lobster genus Paramunida. Analyses of the molecular phylogeny revealed an accelerated diversification in the late Oligocene-Miocene followed by a slowdown in the rate of lineage accumulation over time. A parametric biogeographical reconstruction showed the importance of the southwest Pacific area, specifically the island arc of Fiji, Tonga, Vanuatu, Wallis, and Futuna, for diversification of squat lobsters, probably associated with the global warming, high tectonic activity, and changes in oceanic currents that took place in this region during the Oligocene-Miocene period. These results add strong evidence to the hypothesis that the Neogene was a period of major diversification for marine organisms in both shallow and deep waters. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

Late Cenozoic sedimentation and volcanism during transtensional deformation in Wingate Wash and the Owlshead Mountains, Death Valley

USGS Publications Warehouse

Luckow, H.G.; Pavlis, T.L.; Serpa, L.F.; Guest, B.; Wagner, D.L.; Snee, L.; Hensley, T.M.; Korjenkov, A.

2005-01-01

New 1:24,000 scale mapping, geochemical analyses of volcanic rocks, and Ar/Ar and tephrochronology analyses of the Wingate Wash, northern Owlshead Mountain and Southern Panamint Mountain region document a complex structural history constrained by syntectonic volcanism and sedimentation. In this study, the region is divided into five structural domains with distinct, but related, histories: (1) The southern Panamint domain is a structurally intact, gently south-tilted block dominated by a middle Miocene volcanic center recognized as localized hypabyssal intrusives surrounded by proximal facies pyroclastic rocks. This Miocene volcanic sequence is an unusual alkaline volcanic assemblage ranging from trachybasalt to rhyolite, but dominated by trachyandesite. The volcanic rocks are overlain in the southwestern Panamint Mountains by a younger (Late Miocene?) fanglomerate sequence. (2) An upper Wingate Wash domain is characterized by large areas of Quaternary cover and complex overprinting of older structure by Quaternary deformation. Quaternary structures record ???N-S shortening concurrent with ???E-W extension accommodated by systems of strike-slip and thrust faults. (3) A central Wingate Wash domain contains a complex structural history that is closely tied to the stratigraphic evolution. In this domain, a middle Miocene volcanic package contains two distinct assemblages; a lower sequence dominated by alkaline pyroclastic rocks similar to the southern Panamint sequence and an upper basaltic sequence of alkaline basalt and basanites. This volcanic sequence is in turn overlain by a coarse clastic sedimentary sequence that records the unroofing of adjacent ranges and development of ???N-S trending, west-tilted fault blocks. We refer to this sedimentary sequence as the Lost Lake assemblage. (4) The lower Wingate Wash/northern Owlshead domain is characterized by a gently north-dipping stratigraphic sequence with an irregular unconformity at the base developed on granitic basement. The unconformity is locally overlain by channelized deposits of older Tertiary(?) red conglomerate, some of which predate the onset of extensive volcanism, but in most of the area is overlain by a moderately thick package of Middle Miocene trachybasalt, trachyandesitic, ash flows, lithic tuff, basaltic cinder, basanites, and dacitic pyroclastic, debris, and lahar flows with localized exposures of sedimentary rocks. The upper part of the Miocene stratigraphic sequence in this domain is comprised of coarse grained-clastic sediments that are apparently middle Miocene based on Ar/Ar dating of interbedded volcanic rocks. This sedimentary sequence, however, is lithologically indistinguishable from the structurally adjacent Late Miocene Lost Lake assemblage and a stratigraphically overlying Plio-Pleistocene alluvial fan; a relationship that handicaps tracing structures through this domain. This domain is also structurally complex and deformed by a series of northwest-southeast-striking, east-dipping, high-angle oblique, sinistral, normal faults that are cut by left-lateral strike-slip faults. The contact between the southern Panamint domain and the adjacent domains is a complex fault system that we interpret as a zone of Late Miocene distributed sinistral slip that is variably overprinted in different portions of the mapped area. The net sinistral slip across the Wingate Wash fault system is estimated at 7-9 km, based on offset of Proterozoic Crystal Springs Formation beneath the middle Miocene unconformity to as much as 15 km based on offset volcanic facies in Middle Miocene rocks. To the south of Wingate Wash, the northern Owlshead Mountains are also cut by a sinistral, northwest-dipping, oblique normal fault, (referred to as the Filtonny Fault) with significant slip that separates the Lower Wingate Wash and central Owlshead domains. The Filtonny Fault may represent a young conjugate fault to the dextral Southern Death Valley fault system and may be the northwest

Seismic stratigraphy, tectonics and depositional history in the Halk el Menzel region, NE Tunisia

NASA Astrophysics Data System (ADS)

Sebei, Kawthar; Inoubli, Mohamed Hédi; Boussiga, Haïfa; Tlig, Said; Alouani, Rabah; Boujamaoui, Mustapha

2007-01-01

In the Halk el Menzel area, the proximal- to pelagic platform transition and related tectonic events during the Upper Cretaceous-Lower Miocene have not been taken into adequate consideration. The integrated interpretation of outcrop and subsurface data help define a seismic stratigraphic model and clarify the geodynamic evolution of the Halk el Menzel block. The sedimentary column comprises marls and limestones of the Campanian to Upper Eocene, overlain by Oligocene to Lower Miocene aged siliciclastics and carbonates. Well to well correlations show sedimentary sequences vary considerably in lithofacies and thicknesses over short distances with remarkable gaps. The comparison of sedimentary sequences cut by borehole and seismic stratigraphic modelling as well help define ten third order depositional sequences (S1-S10). Sequences S1 through S6 (Campanian-Paleocene) are mainly characterized by oblique to sigmoid configurations with prograding sedimentary structures, whereas, sequences S7-S10 (Ypresian to Middle Miocene) are organized in shallow water deposits with marked clinoform ramp geometry. Sedimentary discontinuities developed at sequence boundaries are thought to indicate widespread fall in relative sea level. Angular unconformities record a transpressive tectonic regime that operated from the Campanian to Upper Eocene. The geometry of sequences with reduced thicknesses, differential dipping of internal seismic reflections and associated normal faulting located westerly in the area, draw attention to a depositional sedimentary system developed on a gentle slope evolving from a tectonically driven steepening towards the Northwest. The seismic profiles help delimit normal faulting control environments of deposition. In contrast, reef build-ups in the Eastern parts occupy paleohighs NE-SW in strike with bordering Upper Maastrichtian-Ypresian seismic facies onlapping Upper Cretaceous counterparts. During the Middle-Upper Eocene, transpressive stress caused reactivation of faults from normal to reverse play. This has culminated in propagation folds located to the west; whereas, the eastern part of the block has suffered progressive subsidence. Transgressive carbonate depositional sequences have predominated during the Middle Miocene and have sealed pre-existing tectonic structures.

Influence of habitat structure on fish assemblage of an artificial reef in southern Brazil.

PubMed

Hackradt, Carlos Werner; Félix-Hackradt, Fabiana Cézar; García-Charton, José Antonio

2011-12-01

Habitat complexity strongly influences reef fish community composition. An understanding of the underlying reasons for this relationship is important for evaluating the suitability of artificial reef (AR) habitats as a marine resource management tool. We studied the influence of AR habitat structure on fish assemblage composition off the southern coast of Brazil. We found that reef blocks with greater area and number of holes possessed the greatest fish species richness and abundance. Reef blocks with greater complexity had higher abundance of almost 30% of fish species present. Natural reef (NR) and AR were different in their fish species composition, trophic structure and categories of water column occupancy by fish (spatial categories). Although NR was more diverse and harboured more trophic levels, AR presented the higher abundances and the presence of distinct fish species that underlined their importance at a regional scale. The greater availability of sheltering habitat where hard substrate is scarce, together with their frequent use by economically important species, make AR a useful tool for coastal management when certain ecological conditions are met. Copyright © 2011 Elsevier Ltd. All rights reserved.

Historical Trends in pH and Carbonate Biogeochemistry on the Belize Mesoamerican Barrier Reef System

NASA Astrophysics Data System (ADS)

Fowell, S. E.; Foster, G. L.; Ries, J. B.; Castillo, K. D.; de la Vega, E.; Tyrrell, T.; Donald, H. K.; Chalk, T. B.

2018-04-01

Coral reefs are important ecosystems that are increasingly negatively impacted by human activities. Understanding which anthropogenic stressors play the most significant role in their decline is vital for the accurate prediction of future trends in coral reef health and for effective mitigation of these threats. Here we present annually resolved boron and carbon isotope measurements of two cores capturing the past 90 years of growth of the tropical reef-building coral Siderastrea siderea from the Belize Mesoamerican Barrier Reef System. The pairing of these two isotope systems allows us to parse the reconstructed pH change into relative changes in net ecosystem productivity and net ecosystem calcification between the two locations. This approach reveals that the relationship between seawater pH and coral calcification, at both a colony and ecosystem level, is complex and cannot simply be modeled as linear or even positive. This study also underscores both the utility of coupled δ11B-δ13C measurements in tracing past biogeochemical cycling in coral reefs and the complexity of this cycling relative to the open ocean.

Seaweed beds support more juvenile reef fish than seagrass beds in a south-western Atlantic tropical seascape

NASA Astrophysics Data System (ADS)

Eggertsen, L.; Ferreira, C. E. L.; Fontoura, L.; Kautsky, N.; Gullström, M.; Berkström, C.

2017-09-01

Seascape connectivity is regarded essential for healthy reef fish communities in tropical shallow systems. A number of reef fish species use separate adult and nursery habitats, and hence contribute to nutrient and energy transfer between habitats. Seagrass beds and mangroves often constitute important nursery habitats, with high structural complexity and protection from predation. Here, we investigated if reef fish assemblages in the tropical south-western Atlantic demonstrate ontogenetic habitat connectivity and identify possible nurseries on three reef systems along the eastern Brazilian coast. Fish were surveyed in fore reef, back reef, Halodule wrightii seagrass beds and seaweed beds. Seagrass beds contained lower abundances and species richness of fish than expected, while Sargassum-dominated seaweed beds contained significantly more juveniles than all other habitats (average juvenile fish densities: 32.6 per 40 m2 in Sargassum beds, 11.2 per 40 m2 in back reef, 10.1 per 40 m2 in fore reef, and 5.04 per 40 m2 in seagrass beds), including several species that are found in the reef habitats as adults. Species that in other regions worldwide (e.g. the Caribbean) utilise seagrass beds as nursery habitats were here instead observed in Sargassum beds or back reef habitats. Coral cover was not correlated to adult fish distribution patterns; instead, type of turf was an important variable. Connectivity, and thus pathways of nutrient transfer, seems to function differently in east Brazil compared to many tropical regions. Sargassum-dominated beds might be more important as nurseries for a larger number of fish species than seagrass beds. Due to the low abundance of structurally complex seagrass beds we suggest that seaweed beds might influence adult reef fish abundances, being essential for several keystone species of reef fish in the tropical south-western Atlantic.

Spider crabs of the Western Atlantic with special reference to fossil and some modern Mithracidae

PubMed Central

Portell, Roger W.; Klier, Aaron T.; Prueter, Vanessa; Tucker, Alyssa L.

2015-01-01

Spider crabs (Majoidea) are well-known from modern oceans and are also common in the western part of the Atlantic Ocean. When spider crabs appeared in the Western Atlantic in deep time, and when they became diverse, hinges on their fossil record. By reviewing their fossil record, we show that (1) spider crabs first appeared in the Western Atlantic in the Late Cretaceous, (2) they became common since the Miocene, and (3) most species and genera are found in the Caribbean region from the Miocene onwards. Furthermore, taxonomic work on some modern and fossil Mithracidae, a family that might have originated in the Western Atlantic, was conducted. Specifically, Maguimithrax gen. nov. is erected to accommodate the extant species Damithrax spinosissimus, while Damithrax cf. pleuracanthus is recognized for the first time from the fossil record (late Pliocene–early Pleistocene, Florida, USA). Furthermore, two new species are described from the lower Miocene coral-associated limestones of Jamaica (Mithrax arawakum sp. nov. and Nemausa windsorae sp. nov.). Spurred by a recent revision of the subfamily, two known species from the same deposits are refigured and transferred to new genera: Mithrax donovani to Nemausa, and Mithrax unguis to Damithrax. The diverse assemblage of decapods from these coral-associated limestones underlines the importance of reefs for the abundance and diversity of decapods in deep time. Finally, we quantitatively show that these crabs possess allometric growth in that length/width ratios drop as specimens grow, a factor that is not always taken into account while describing and comparing among taxa. PMID:26557432

Ecohydrodynamics of cold-water coral reefs: a case study of the Mingulay Reef Complex (western Scotland).

PubMed

Moreno Navas, Juan; Miller, Peter I; Miller, Peter L; Henry, Lea-Anne; Hennige, Sebastian J; Roberts, J Murray

2014-01-01

Ecohydrodynamics investigates the hydrodynamic constraints on ecosystems across different temporal and spatial scales. Ecohydrodynamics play a pivotal role in the structure and functioning of marine ecosystems, however the lack of integrated complex flow models for deep-water ecosystems beyond the coastal zone prevents further synthesis in these settings. We present a hydrodynamic model for one of Earth's most biologically diverse deep-water ecosystems, cold-water coral reefs. The Mingulay Reef Complex (western Scotland) is an inshore seascape of cold-water coral reefs formed by the scleractinian coral Lophelia pertusa. We applied single-image edge detection and composite front maps using satellite remote sensing, to detect oceanographic fronts and peaks of chlorophyll a values that likely affect food supply to corals and other suspension-feeding fauna. We also present a high resolution 3D ocean model to incorporate salient aspects of the regional and local oceanography. Model validation using in situ current speed, direction and sea elevation data confirmed the model's realistic representation of spatial and temporal aspects of circulation at the reef complex including a tidally driven current regime, eddies, and downwelling phenomena. This novel combination of 3D hydrodynamic modelling and remote sensing in deep-water ecosystems improves our understanding of the temporal and spatial scales of ecological processes occurring in marine systems. The modelled information has been integrated into a 3D GIS, providing a user interface for visualization and interrogation of results that allows wider ecological application of the model and that can provide valuable input for marine biodiversity and conservation applications.

Ecohydrodynamics of Cold-Water Coral Reefs: A Case Study of the Mingulay Reef Complex (Western Scotland)

PubMed Central

Navas, Juan Moreno; Miller, Peter L.; Henry, Lea-Anne; Hennige, Sebastian J.; Roberts, J. Murray

2014-01-01

Ecohydrodynamics investigates the hydrodynamic constraints on ecosystems across different temporal and spatial scales. Ecohydrodynamics play a pivotal role in the structure and functioning of marine ecosystems, however the lack of integrated complex flow models for deep-water ecosystems beyond the coastal zone prevents further synthesis in these settings. We present a hydrodynamic model for one of Earth's most biologically diverse deep-water ecosystems, cold-water coral reefs. The Mingulay Reef Complex (western Scotland) is an inshore seascape of cold-water coral reefs formed by the scleractinian coral Lophelia pertusa. We applied single-image edge detection and composite front maps using satellite remote sensing, to detect oceanographic fronts and peaks of chlorophyll a values that likely affect food supply to corals and other suspension-feeding fauna. We also present a high resolution 3D ocean model to incorporate salient aspects of the regional and local oceanography. Model validation using in situ current speed, direction and sea elevation data confirmed the model's realistic representation of spatial and temporal aspects of circulation at the reef complex including a tidally driven current regime, eddies, and downwelling phenomena. This novel combination of 3D hydrodynamic modelling and remote sensing in deep-water ecosystems improves our understanding of the temporal and spatial scales of ecological processes occurring in marine systems. The modelled information has been integrated into a 3D GIS, providing a user interface for visualization and interrogation of results that allows wider ecological application of the model and that can provide valuable input for marine biodiversity and conservation applications. PMID:24873971

Topographic control and accumulation rate of some Holocene coral reefs: south Florida and Dry Tortugas

USGS Publications Warehouse

Shinn, E.A.; Hudson, J.H.; Halley, R.B.; Lidz, B.H.; Taylor, D.L.

1977-01-01

Core drilling and examination of underwater excavation on 6 reef sites in south Florida and Dry Tortugas revealed that underlying topography is the major factor controlling reef morphology. Carbon-14 dating on coral recovered from cores enables calculation of accumulation rates. Accumulation rates were found to range from 0.38 m/1000 years in thin Holocene reefs to as much as 4.85 m/1000 years in thicker buildups. Cementation and alteration of corals were found to be more pronounced in areas of low buildup rates than in areas of rapid accumulation rates. Acropora palmata, generally considered the major reef builder in Florida, was found to be absent in most reefs drilled. At Dry Tortugas, the more than 13-meter thick Holocene reef did not contain A. palmata. The principal reef builders in this outer reef are the same as those which built the Pleistocene Key Largo formation, long considered to be fossilized patch reef complex.

Impact of sea-level rise and coral mortality on the wave dynamics and wave forces on barrier reefs.

PubMed

Baldock, T E; Golshani, A; Callaghan, D P; Saunders, M I; Mumby, P J

2014-06-15

A one-dimensional wave model was used to investigate the reef top wave dynamics across a large suite of idealized reef-lagoon profiles, representing barrier coral reef systems under different sea-level rise (SLR) scenarios. The modeling shows that the impacts of SLR vary spatially and are strongly influenced by the bathymetry of the reef and coral type. A complex response occurs for the wave orbital velocity and forces on corals, such that the changes in the wave dynamics vary reef by reef. Different wave loading regimes on massive and branching corals also leads to contrasting impacts from SLR. For many reef bathymetries, wave orbital velocities increase with SLR and cyclonic wave forces are reduced for certain coral species. These changes may be beneficial to coral health and colony resilience and imply that predicting SLR impacts on coral reefs requires careful consideration of the reef bathymetry and the mix of coral species. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reconnaissance geology of the Manjamah Quadrangle, sheet 18/41 A, Kingdom of Saudi Arabia

USGS Publications Warehouse

Hadley, D.G.

1982-01-01

The Manjamah quadrangle (sheet 18/41 A) lies between lat 18?30' and 19?00' N. and long 41?00' and 41?30' E. and encompasses an area of 2,932 km2, of which about half is land and the remainder covered by the Red Sea. The geologic formations exposed in the quadrangle comprise Precambrian layered and intrusive rocks,. Tertiary layered rocks and gabbro dikes, and. Quaternary basaltic lavas, pyroclastic rocks, and surficial deposits. The Precambrian rocks are layered metasedimentary and metavolcanic rocks that have been assigned to the Baish and Bahah groups. These rocks are cut by Precambrian biotite quartz monzonite and by Miocene gabbro dikes that were intruded during the initial stages of the opening of the Red Sea rift. Tuffaceous siltstone of the Baid formation was also deposited during the Miocene, followed in the Pliocene by the polymict conglomerate of the Bathan formation. The Quaternary rocks include basalt that was extruded during a continuation of the opening of the Red Sea rift, after uplift of the escarpment parallel with the Red Sea but before the Holocene erosional cycle. The greater part of the land area of the quadrangle is covered by Quaternary coastal, pediment, and alluvial deposits of various kinds associated with the deltaic mouths of Wadi Hall and Wadi Yiba and their tributaries and with the development of fringing reefs and islands. The area also contains extensive Quaternary eolian deposits. The economic potential of the quadrangle lies essentially in the agricultural value .of its flood-plain deposits, which are frequently refreshed during flooding with the products of weathering and erosion of the Precambrian rocks in the valleys of Wadi Hal i and Wadi Yiba; coral reefs could possibly provide raw material for use in a cement industry, if any such industry were ever required in this area.

Multi-scale Onland-Offshore Investigations of the New Caledonia Ophiolite, SW Pacific

NASA Astrophysics Data System (ADS)

Clerc, C. N.; Collot, J.; Sevin, B.; Patriat, M.; Etienne, S.; Iseppi, M.; Lesimple, S.; Jeanpert, J.; Mortimer, N. N.; Poli, S.; Pattier, F.; Juan, C.; Robineau, B.; Godard, M.; Cluzel, D.

2017-12-01

The Peridotite Nappe of New Caledonia is one of the largest ultramafic ophiolite in the World: it represents about one quarter of the 500 x 80 km island of Grande Terre. This extensive upper mantle unit was tectonically emplaced during the Eocene onto the northeastern edge of Zealandia continent. It is weakly deformed because it was not involved in a collision belt after obduction. A dome-shaped Eocene HP/LT metamorphic complex was exhumed across the fore-arc mantle lithosphere in the northern tip of the island. Post-obduction Miocene to Present coral reefs developed in shallow waters around Grande Terre and surrounding islands. In the perspective of a possible onshore/offshore drilling project (IODP/ICDP), we present recent advances in our understanding of offshore extensions of this ophiolite. To the south of New Caledonia, the offshore continuation of the ultramafic allochthon has been identified by dredges and by its geophysical signature as a continuous linear body that extends over a distance of more than 400 km at about 2000m bsl. Such water depths allow an unprecedented seismic reflection imaging of a drowned and well-preserved ophiolite. Seismic profiles show that the nappe has a flat-top, and is capped by carbonate reefs and dissected by several major normal faults. To the east of this presumed ultramafic body, Felicité Ridge is a 30 km wide, 350 km long, dome-shaped ridge, which may be interpreted as the possible southern extension of the HP/LT metamorphic complex observed onshore. Onshore, several 150 to 200 m long cores were drilled in the ophiolite and airborne electromagnetic allowed high-resolution imaging down to 400 m depth. These recent results allow identification of internal thrusts within the peridotite body and more superficial landslides. The analysis of polyphase fracturation and associated serpentinization brings new constraints on the tectonic evolution of the ophiolite and its subsequent weathering pattern. We integrate these data and discuss the chronology of pre-, syn-, and post-obduction tectonic events. But our limited access to the deep parts of the ophiolite calls for the necessity of planning an onshore/offshore deep drilling project.

Eocene and Miocene extension, meteoric fluid infiltration, and core complex formation in the Great Basin (Raft River Mountains, Utah)

USGS Publications Warehouse

Methner, Katharina; Mulch, Andreas; Teyssier, Christian; Wells, Michael L.; Cosca, Michael A.; Gottardi, Raphael; Gebelin, Aude; Chamberlain, C. Page

2015-01-01

Metamorphic core complexes (MCCs) in the North American Cordillera reflect the effects of lithospheric extension and contribute to crustal adjustments both during and after a protracted subduction history along the Pacific plate margin. While the Miocene-to-recent history of most MCCs in the Great Basin, including the Raft River-Albion-Grouse Creek MCC, is well documented, early Cenozoic tectonic fabrics are commonly severely overprinted. We present stable isotope, geochronological (40Ar/39Ar), and microstructural data from the Raft River detachment shear zone. Hydrogen isotope ratios of syntectonic white mica (δ2Hms) from mylonitic quartzite within the shear zone are very low (−90‰ to −154‰, Vienna SMOW) and result from multiphase synkinematic interaction with surface-derived fluids. 40Ar/39Ar geochronology reveals Eocene (re)crystallization of white mica with δ2Hms ≥ −154‰ in quartzite mylonite of the western segment of the detachment system. These δ2Hms values are distinctively lower than in localities farther east (δ2Hms ≥ −125‰), where 40Ar/39Ar geochronological data indicate Miocene (18–15 Ma) extensional shearing and mylonitic fabric formation. These data indicate that very low δ2H surface-derived fluids penetrated the brittle-ductile transition as early as the mid-Eocene during a first phase of exhumation along a detachment rooted to the east. In the eastern part of the core complex, prominent top-to-the-east ductile shearing, mid-Miocene 40Ar/39Ar ages, and higher δ2H values of recrystallized white mica, indicate Miocene structural and isotopic overprinting of Eocene fabrics.

Coral reef resilience through biodiversity

USGS Publications Warehouse

Rogers, Caroline S.

2013-01-01

Irrefutable evidence of coral reef degradation worldwide and increasing pressure from rising seawater temperatures and ocean acidification associated with climate change have led to a focus on reef resilience and a call to “manage” coral reefs for resilience. Ideally, global action to reduce emission of carbon dioxide and other greenhouse gases will be accompanied by local action. Effective management requires reduction of local stressors, identification of the characteristics of resilient reefs, and design of marine protected area networks that include potentially resilient reefs. Future research is needed on how stressors interact, on how climate change will affect corals, fish, and other reef organisms as well as overall biodiversity, and on basic ecological processes such as connectivity. Not all reef species and reefs will respond similarly to local and global stressors. Because reef-building corals and other organisms have some potential to adapt to environmental changes, coral reefs will likely persist in spite of the unprecedented combination of stressors currently affecting them. The biodiversity of coral reefs is the basis for their remarkable beauty and for the benefits they provide to society. The extraordinary complexity of these ecosystems makes it both more difficult to predict their future and more likely they will have a future.

Old stories and lost pieces of the Eastern Mediterranean puzzle: a new approach to the tectonic evolution of the Western Anatolia and the Aegean Sea

NASA Astrophysics Data System (ADS)

Yaltırak, Cenk; Engin Aksu, Ali; Hall, Jeremy; Elitez, İrem

2015-04-01

During the last 20 or so years, the tectonic evolution of Aegean Sea and Western Anatolia has been dominantly explained by back-arc extension and escape tectonics along the North Anatolian Fault. Various datasets have been considered in the construction of general tectonic models, including the geometry of fault patterns, paleomagnetic data, extensional directions of the core complexes, characteristic changes in magmatism and volcanism, the different sense of Miocene rotation between the opposite sides of the Aegean Sea, and the stratigraphy and position of the Miocene and Pliocene-Quaternary basins. In these models, the roles of the Burdur-Fethiye Shear Zone, the Trakya-Eskişehir Fault Zone, the Anaximander Mountains and Isparta Angle have almost never been taken into consideration. The holistic evaluation of numerous land and marine researches in the Aegean Sea and western Anatolia suggest the following evolutionary stages: 1. during the early Miocene, Greece and western Anatolia were deformed under the NE-SW extensional tectonics associated with the back-arc extension, when core complexes and supra-detachment basins developed, 2. following the collision of the Anaximander Mountains and western Anatolia in early Miocene , the Isparta Angle locked this side of the western arc by generating a triangle-shaped compressional structure, 3. while the Isparta Angle penetrated into the Anatolia, the NE-striking Burdur-Fethiye Shear Zone in the west and NW-striking Trakya-Eskişehir Fault Zone in the north developed along the paleo-tectonic zones , 4. the formation of these two tectonic structures allowed the counterclockwise rotation of the western Anatolia in the middle Miocene and this rotation removed the effect of the back-arc extension on the western Anatolian Block, 5. the counterclockwise rotation developed with the early westward escape of the Western Anatolian reached up to 35-40o and Trakya-Eskişehir Fault Zone created a total dextral displacement of about 200 km. Therefore the original NE-SW extension records on the core complexes rotated to the N-S orientation and replace 45o in reference to the core complexes in Greece, 6. During this stage, the left-lateral shear along the Burdur-Fethiye Shear Zone indicates the southern part of the counterclockwise rotation. 7. The North Anatolian Fault started to form as the result of the collision of the Arabian Microplate and the Eurasian Plate in the late Miocene. This continental transform fault propagated into the Marmara Region in the late Pliocene. Its late westward escape by cutting the Trakya-Eskişehir Fault Zone on three points generates its transportation through Trakya-Eskişehir Fault Zone splays. 8. During the Miocene, while Greece was rotating 20o clockwise and continuing to be shaped by the NW-SE normal faults, which were formed as a result of back-arc tectonic, the late westward escape of the Anatolia changed the orientation of the NEE-SWW striking oblique-extensional fault-controlled Miocene basins to NE-SW direction. The rotational E-W basins, which had developed by the North Anatolian Fault tectonics, superimposed with these Miocene basins .

The future of coral reefs in the US Virgin Islands: is Acropora palmata more likely to recover than Montastraea annularis complex?

USGS Publications Warehouse

Rogers, Caroline S.; Muller, Erinn; Spitzack, Tony; Miller, Jeff

2008-01-01

Coral diseases have played a major role in the degradation of coral reefs in the Caribbean, including those in the US Virgin Islands (USVI). In 2005, bleaching affected reefs throughout the Caribbean, and was especially severe on USVI reefs. Some corals began to regain their color as water temperatures cooled, but an outbreak of disease (primarily white plague) led to losses of over 60% of the total live coral cover. Montastraea annularis, the most abundant coral, was disproportionately affected, and decreased in relative abundance. The threatened species Acropora palmata bleached for the first time on record in the USVI but suffered less bleaching and less mortality from disease than M. annularis. Acropora palmata and M. annularis are the two most significant species in the USVI because of their structural role in the architecture of the reefs, the large size of their colonies, and their complex morphology. The future of the USVI reefs depends largely on their fate. Acropora palmata is more likely to recover than M. annularis for many reasons, including its faster growth rate, and its lower vulnerability to bleaching and disease.

African and Asian dust: from desert soils to coral reefs

USGS Publications Warehouse

Garrison, Virginia H.; Shinn, Eugene A.; Foreman, William T.; Griffin, Dale W.; Holmes, Charles W.; Kellogg, Christina A.; Majewski, Michael S.; Richardson, Laurie L.; Ritchie, Kim B.; Smith, Garriet W.

2003-01-01

Many hypotheses have been proposed to explain the decline of coral reefs throughout the world, but none adequately accounts for the lack of recovery of reefs or the wide geographical distribution of coral diseases. The processes driving the decline remain elusive. Hundreds of millions of tons of dust transported annually from Africa and Asia to the Americas may be adversely affecting coral reefs and other downwind ecosystems. Viable microorganisms, macro- and micronutrients, trace metals, and an array of organic contaminants carried in the dust air masses and deposited in the oceans and on land may play important roles in the complex changes occurring on coral reefs worldwide.

Predicting Coral Recruitment in Palau’s Complex Reef Archipelago

PubMed Central

Golbuu, Yimnang; Wolanski, Eric; Idechong, Jacques Wasai; Victor, Steven; Isechal, Adelle Lukes; Oldiais, Noelle Wenty; Idip, David; Richmond, Robert H.; van Woesik, Robert

2012-01-01

Reproduction and recruitment are key processes that replenish marine populations. Here we use the Palau archipelago, in the western Pacific Ocean, as a case study to examine scales of connectivity and to determine whether an oceanographic model, incorporating the complex reef architecture, is a useful predictor of coral recruitment. We tested the hypothesis that the reefs with the highest retention also had the highest densities of juvenile coral density from 80 field sites. Field comparisons showed a significant correlation between the densities of juvenile Acropora colonies and total larval recruitment derived from the model (i.e., calculated as the sum of the densities of larvae that self-seeded and recruited from the other reefs in the archipelago). Long-distance larval imports may be too infrequent to sustain coral populations, but are critical for recovery in times of extreme local stress. PMID:23209842

First description of a Lophelia pertusa reef complex in Atlantic Canada

NASA Astrophysics Data System (ADS)

Buhl-Mortensen, Pål; Gordon, Don C.; Buhl-Mortensen, Lene; Kulka, Dave W.

2017-08-01

For the first time, we describe a cold-water coral reef complex in Atlantic Canada, discovered at the shelf break, in the mouth of the Laurentian Channel. The study is based on underwater video and sidescan sonar. The reef complex covered an area of approximately 490×1300 m, at 280-400 m depth. It consisted of several small mounds (< 3 m high) where the scleractinian Lophelia pertusa occurred as live colonies, dead blocks and skeletal rubble. On the mounds, a total of 67 live colonies occurred within 14 patches at 300-320 m depth. Most of these (67%) were small (< 20 cm high). Dead coral (rubble and blocks), dominated (88% of all coral observations). Extensive signs of damage by bottom-fishing gear were observed: broken and tilted coral colonies, over-turned boulders and lost fishing gear. Fisheries observer data indicated that the reef complex was subjected to heavy otter trawling annually between 1980 and 2000. In June 2004, a 15 km2 conservation area excluding all bottom-fishing was established. Current bottom fisheries outside the closure include otter trawling for redfish and anchored longlines for halibut. Vessel monitoring system data indicate that the closure is generally respected by the fishing industry.

iss009e23808

NASA Image and Video Library

2004-09-20

ISS009-E-23808 (20 September 2004) --- A fringing coral reef in the Red Sea is featured in this image photographed by an Expedition 9 crewmember on the International Space Station (ISS). The Sudanese coast of the Red Sea is a well known destination for divers due to clear water and abundance of coral reefs (or “shia’ab” in Arabic). According to NASA scientists studying the ISS imagery, reefs are formed primarily from precipitation of calcium carbonate by corals; massive reef structures are built over thousands of years of succeeding generations of coral. In the Red Sea, fringing reefs form on shallow shelves of less than 50 meters depth along the coastline. This photograph illustrates the intricate morphology of the reef system located along the coast between Port Sudan to the northwest and the Tokar River delta to the southeast. Close to shore, fringing reefs border the coastline. Farther offshore grows a larger, more complicated barrier reef structure. Different parts of the reef structure show up as variable shades of light blue. Deeper water channels (darker blue) define the boundaries for individual reefs within the greater barrier reef system. Such a complex pattern of reefs may translate into greater ecosystem diversity through a wide variety of local reef environments.

The Misis-Andırın Complex: a Mid-Tertiary melange related to late-stage subduction of the Southern Neotethys in S Turkey

NASA Astrophysics Data System (ADS)

Robertson, Alastair; Unlügenç, Ülvi Can; İnan, Nurdan; Ta ṡli, Kemal

2004-01-01

The Mid-Tertiary (Mid-Eocene to earliest Miocene) Misis-Andırın Complex documents tectonic-sedimentary processes affecting the northerly, active margin of the South Tethys (Neotethys) in the easternmost Mediterranean region. Each of three orogenic segments, Misis (in the SW), Andırın (central) and Engizek (in the NE) represent parts of an originally continuous active continental margin. A structurally lower Volcanic-Sedimentary Unit includes Late Cretaceous arc-related extrusives and their Lower Tertiary pelagic cover. This unit is interpreted as an Early Tertiary remnant of the Mesozoic South Tethys. The overlying melange unit is dominated by tectonically brecciated blocks (>100 m across) of Mesozoic neritic limestone that were derived from the Tauride carbonate platform to the north, together with accreted ophiolitic material. The melange matrix comprises polymict debris flows, high- to low-density turbidites and minor hemipelagic sediments. The Misis-Andırın Complex is interpreted as an accretionary prism related to the latest stages of northward subduction of the South Tethys and diachronous continental collision of the Tauride (Eurasian) and Arabian (African) plates during Mid-Eocene to earliest Miocene time. Slivers of Upper Cretaceous oceanic crust and its Early Tertiary pelagic cover were accreted, while blocks of Mesozoic platform carbonates slid from the overriding plate. Tectonic mixing and sedimentary recycling took place within a trench. Subduction culminated in large-scale collapse of the overriding (northern) margin and foundering of vast blocks of neritic carbonate into the trench. A possible cause was rapid roll back of dense downgoing Mesozoic oceanic crust, such that the accretionary wedge taper was extended leading to gravity collapse. Melange formation was terminated by underthrusting of the Arabian plate from the south during earliest Miocene time. Collision was diachronous. In the east (Engizek Range and SE Anatolia) collision generated a Lower Miocene flexural basin infilled with turbidites and a flexural bulge to the south. Miocene turbiditic sediments also covered the former accretionary prism. Further west (Misis Range) the easternmost Mediterranean remained in a pre-collisional setting with northward underthrusting (incipient subduction) along the Cyprus arc. The Lower Miocene basins to the north (Misis and Adana) indicate an extensional (to transtensional) setting. The NE-SW linking segment (Andırın) probably originated as a Mesozoic palaeogeographic offset of the Tauride margin. This was reactivated by strike-slip (and transtension) during Later Tertiary diachronous collision. Related to on-going plate convergence the former accretionary wedge (upper plate) was thrust over the Lower Miocene turbiditic basins in Mid-Late Miocene time. The Plio-Quaternary was dominated by left-lateral strike-slip along the East Anatolian transform fault and also along fault strands cutting the Misis-Andırın Complex.

The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

USGS Publications Warehouse

Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

2011-01-01

Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

Miocene-Oligocene sequence stratigraphy of the Malay Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovell, R.; Elias, M.R.; Hill, R.E.

1994-07-01

The Malay Basin has experienced extension of the Eocene ( ) through Oligocene, sag in the early Miocene, and compression in the middle Miocene through Pliocene-Pleistocene. The interaction of structurally induced and glacial-eustatic accommodation changes has resulted in complex, interrelated play elements, including multiple reservoirs, diverse nonmarine sources, discontinuous migration pathways, and thin seals. Extensional subbasins were filled with braided streams, associated coastal plain, lacustrine deltas, and thick lake shales (groups M-K). This initial rift fill comprises an overall second order progradational cycle punctuated by 3rd-order cycles. These 3rd-order cycles are capped by thick, source-rich, lacustrine shale packages. The lowermore » Miocene section (groups I and J) consists of progradational to aggradational fluvial to tidally-dominated estuarine sands. Hydrocarbons are generated from interbedded coals and other coal-related lithologies.« less

Ecological solutions to reef degradation: optimizing coral reef restoration in the Caribbean and Western Atlantic

PubMed Central

2016-01-01

Reef restoration activities have proliferated in response to the need to mitigate coral declines and recover lost reef structure, function, and ecosystem services. Here, we describe the recent shift from costly and complex engineering solutions to recover degraded reef structure to more economical and efficient ecological approaches that focus on recovering the living components of reef communities. We review the adoption and expansion of the coral gardening framework in the Caribbean and Western Atlantic where practitioners now grow and outplant 10,000’s of corals onto degraded reefs each year. We detail the steps for establishing a gardening program as well as long-term goals and direct and indirect benefits of this approach in our region. With a strong scientific basis, coral gardening activities now contribute significantly to reef and species recovery, provide important scientific, education, and outreach opportunities, and offer alternate livelihoods to local stakeholders. While challenges still remain, the transition from engineering to ecological solutions for reef degradation has opened the field of coral reef restoration to a wider audience poised to contribute to reef conservation and recovery in regions where coral losses and recruitment bottlenecks hinder natural recovery. PMID:27781176

Ecological solutions to reef degradation: optimizing coral reef restoration in the Caribbean and Western Atlantic.

PubMed

Lirman, Diego; Schopmeyer, Stephanie

2016-01-01

Reef restoration activities have proliferated in response to the need to mitigate coral declines and recover lost reef structure, function, and ecosystem services. Here, we describe the recent shift from costly and complex engineering solutions to recover degraded reef structure to more economical and efficient ecological approaches that focus on recovering the living components of reef communities. We review the adoption and expansion of the coral gardening framework in the Caribbean and Western Atlantic where practitioners now grow and outplant 10,000's of corals onto degraded reefs each year. We detail the steps for establishing a gardening program as well as long-term goals and direct and indirect benefits of this approach in our region. With a strong scientific basis, coral gardening activities now contribute significantly to reef and species recovery, provide important scientific, education, and outreach opportunities, and offer alternate livelihoods to local stakeholders. While challenges still remain, the transition from engineering to ecological solutions for reef degradation has opened the field of coral reef restoration to a wider audience poised to contribute to reef conservation and recovery in regions where coral losses and recruitment bottlenecks hinder natural recovery.

The Effect of Oyster Reef Morphology on Particulate Transfer in a North Carolina Tidal Creek

NASA Astrophysics Data System (ADS)

Lemon, M. G.; Posey, M.; Mallin, M.; Alphin, T.

2014-12-01

The eastern oyster (Crassostrea virginica) is a vital ecosystem engineer species, providing a number of ecosystem services that structure and maintain estuarine environments through the construction of large, hard-bottom reef complexes. Through suspension feeding, oysters clear the water column of particulates, leading to decreased suspended material and enhanced benthic pelagic coupling. Past field studies have indicated the potential importance of the physical reef structure in regulating the transfer of particulate material in the seston. In order to directly assess the existence of the physical reef effect, multiple field experiments were performed in a small tidal creek estuary along the south eastern coast of North Carolina. Comparison of clearance rates derived from two different in situ methods, one accounting for the physical structure of the oyster reef in addition to oyster filtration and one looking at oyster filtration alone, indicate that the reef structure may increase the amount of particulate removal performed by the reef by more than 4 times the removal performed by oyster filtration alone. A defaunation experiment was performed by eliminating the live component of the oyster reef and comparing particulate transfer of this defaunated transect to that of an adjacent faunated transect. The defaunated transect had reduced but not significantly lower material removal when compared to the faunated transect prior to defaunation. Results from short and long term sediment collection and flow velocity measurements indicate that the physical effect of oyster reefs is strong over short temporal scales (days) but is much smaller when evaluated over longer time periods (months). Generally, large silt and small sand sized material is permanently removed from the seston due to the interaction of oyster reef structure and tidal flows, however the transfer of small and medium sized silt grains is only slowed down by the presence of large reef complexes. This effect has important ecological implications for downstream water quality and must be accounted for when modeling water quality improvements performed by oysters.

Oyster reef restoration in the Northern Gulf of Mexico: effect of artificial substrate and sge on nekton and benthic macroinvertebrate assemblage use

USGS Publications Warehouse

Brown, Laura A.; Furlong, Jessica N.; Brown, Kenneth M.; LaPeyre, Megan K.

2013-01-01

In the northern Gulf of Mexico (GOM), reefs built by eastern oysters, Crassostrea virginica, provide critical habitat within shallow estuaries, and recent efforts have focused on restoring reefs to benefit nekton and benthic macroinvertebrates. We compared nekton and benthic macroinvertebrate assemblages at historic, newly created (<5years) and old (>6years) shell and rock substrate reefs. Using crab traps, gill-nets, otter trawls, cast nets, and benthic macroinvertebrate collectors, 20 shallow reefs (<5m) in the northern GOM were sampled throughout the summer of 2011. We compared nekton and benthic assemblage abundance, diversity and composition across reef types. Except for benthic macroinvertebrate abundance, which was significantly higher on old rock reefs as compared to historic reefs, all reefs were similar to historic reefs, suggesting created reefs provide similar support of nekton and benthic assemblages as historic reefs. To determine refuge value of oyster structure for benthic macroinvertebrates compared to bare bottom, we tested preferences of juvenile crabs across depth and refuge complexity in the presence and absence of adult blue crabs (Callinectes sapidus). Juveniles were more likely to use deep water with predators present only when provided oyster structure. Provision of structural material to support and sustain development of benthic and mobile reef communities may be the most important factor in determining reef value to these assemblages, with biophysical characteristics related to reef location influencing assemblage patterns in areas with structure; if so, appropriately locating created reefs is critical.

ASSESSMENT OF CORAL CONDITION

EPA Science Inventory

Complex reef structures formed by calcified coral skeletons provide a physical habitat that produces highly-valued ecosystem services, including shoreline protection and a high diversity and abundance of marine organisms that support lucrative fishing and tourism. Yet, coral reef...

USGS research on Atlantic coral reef ecosystems

USGS Publications Warehouse

Kuffner, Ilsa B.; Yates, Kimberly K.; Zawada, David G.; Richey, Julie N.; Kellogg, Christina A.; Toth, Lauren T.

2015-10-23

Coral reefs are massive, biomineralized structures that protect coastal communities by acting as barriers to hazards such as hurricanes and tsunamis. They provide sand for beaches through the natural process of erosion, support tourism and recreational industries, and provide essential habitat for fisheries. The continuing global degradation of coral reef ecosystems is well documented. There is a need for focused, coordinated science to understand the complex physical and biological processes and interactions that are impacting the condition of coral reefs and their ability to respond to a changing environment.

Frictional wave dissipation on a remarkably rough reef

NASA Astrophysics Data System (ADS)

Monismith, Stephen G.; Rogers, Justin S.; Koweek, David; Dunbar, Robert B.

2015-05-01

We present a week of observations of wave dissipation on the south forereef of Palmyra Atoll. Using wave measurements made in 6.2 m and 11.2 m of water offshore of the surf zone, we computed energy fluxes and near-bottom velocity. Equating the divergence of the shoreward energy flux to its dissipation by bottom friction and parameterizating dissipation in terms of the root-mean-square velocity cubed, we find that the wave friction factor, fw, for this reef is 1.80 ± 0.07, nearly an order of magnitude larger than values previously found for reefs. We attribute this remarkably high value of fw to the complex canopy structure of the reef, which we believe may be characteristic of healthy reefs. This suggests that healthy reefs with high coral cover may provide greater coastal protection than do degraded reefs with low coral cover.

Shifts in coral-assemblage composition do not ensure persistence of reef functionality.

PubMed

Alvarez-Filip, Lorenzo; Carricart-Ganivet, Juan P; Horta-Puga, Guillermo; Iglesias-Prieto, Roberto

2013-12-12

Coral communities are changing rapidly worldwide through loss of coral cover and shifts in species composition. Although many reef-building corals are likely to decline, some weedy opportunistic species might increase in abundance. Here we explore whether the reshuffling of species can maintain ecosystem integrity and functioning. Using four common Caribbean reef-building coral genera we modeled rates of reef construction and complexity. We show that shifting coral assemblages result in rapid losses in coral-community calcification and reef rugosity that are independent of changes in the total abundance of reef corals. These losses are considerably higher than those recently attributed to climate change. Dominance patterns of coral assemblages seem to be the most important driver of the functioning of coral reefs and thus, the future of these ecosystems might depend not only on reductions of local and global stressors, but also on the maintenance of keystone coral species.

Planning and management of the Nido Reef Complex Oil Field development, Philippines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harry, R.Y.

1981-01-01

As Operator for the Northeast Palawan consortium, Philippines-Cities Service, Inc., commenced the Philippines first commercial offshore oil production from the Nido Reef Complex Oil Field on February 1, 1979, some 11 months after a decision by management to start development. The relative speed at which design, fabrication, and construction were accomplished is attributed to the use of the concepts of project planning, task force approach, and project management. This paper presents the above concepts as applied to the Nido Complex.

Sulfide saturation history of the Stillwater Complex, Montana: chemostratigraphic variation in platinum group elements

NASA Astrophysics Data System (ADS)

Keays, Reid R.; Lightfoot, Peter C.; Hamlyn, Paul R.

2012-01-01

A platinum group element (PGE) investigation of a 5.3 km-thick stratigraphic section of the Stillwater Complex, Montana was undertaken to refine and test a geochemical technique to explore for platiniferous horizons in layered mafic/ultramafic complexes. PGE, Au, major, and trace elements were determined in 92 samples from outcrops along traverses in the Chrome Mountain and Contact Mountain areas in the western part of the Stillwater Complex where the J-M reef occurs ˜1,460 m above the floor of the intrusion. A further 29 samples from a drill hole cored in the immediate vicinity of the J-M reef were analyzed to detail compositional variations directly above and below the J-M reef. Below the J-M reef, background concentrations of Pt (10 ppb) and Pd (7 ppb) are features of peridotites with intermediate S concentrations (mostly 100-200 ppm) and rocks from the Bronzitite, Norite I, and Gabbronorite I zones (mostly <100 ppm S). A sustained increase in S abundance commences at the J-M reef and continues to increase and peaks in the center of the 600 m-thick middle banded series. Over this same interval, Pt, Pd, and Au are initially elevated and then decrease in the order Pd > Pt > Au. Within the middle and upper banded series, S abundances fluctuate considerably, but exhibit an overall upward increase. The behavior of these elements records periodic sulfide saturation during deposition of the Peridotite zone, followed by crystallization under sulfide-undersaturated conditions until saturation is achieved at the base of the J-M reef. Following formation of the reef, sulfide-saturated conditions persisted throughout the deposition of most of the remaining Lower Layered Series. This resulted in a pronounced impoverishment in PGE abundance in the remaining magma, a condition that continued throughout deposition of the remainder of a succession, which is characterized by very low Pt (1.5 ppb) and Pd (0.7 ppb) abundances. Because only unmineralized rock was selected for study in the 5.3 km-thick section, the results provide an unbiased picture of the variation in background PGE levels during crystallization of the Stillwater Complex. In contrast, the variations in the drill core samples through the reef provide a detailed record of ore formation. Plots of Pt, Pd, Pd/S, and Pt + Pd as a function of stratigraphic height in the intrusion show that the location of the J-M reef is defined by an abrupt change in these concentrations and ratios. Although this is the most abrupt change, three other anomalies in PGE abundance and ratios are apparent in the profiles and coincide with known laterally extensive sub-economic sulfide concentrations above the J-M reef. The uppermost of these is the PGE-bearing Picket Pin sulfide horizon. The relative ease with which mineralized horizons can be pinpointed in these diagrams indicates that a similar approach could be used in exploration programs in other ultramafic/mafic intrusions. Our observations exclude the possibilities of either magma mixing within the Stillwater chamber or the fluxing of a volatile-rich fluid as the mechanisms responsible for the genesis of the J-M reef. Rather, our data indicate that the J-M reef formed from a parental magma that was strongly enriched in PGE; this magma likely formed at depth below the Stillwater magma chamber by the interaction of the parental magma with S-rich meta-sedimentary rocks, followed by the re-dissolution of these sulfides in the Stillwater magma.

Impact of sea-level rise on cross-shore sediment transport on fetch-limited barrier reef island beaches under modal and cyclonic conditions.

PubMed

Baldock, T E; Golshani, A; Atkinson, A; Shimamoto, T; Wu, S; Callaghan, D P; Mumby, P J

2015-08-15

A one-dimensional wave model is combined with an analytical sediment transport model to investigate the likely influence of sea-level rise on net cross-shore sediment transport on fetch-limited barrier reef and lagoon island beaches. The modelling considers if changes in the nearshore wave height and wave period in the lagoon induced by different water levels over the reef flat are likely to lead to net offshore or onshore movement of sediment. The results indicate that the effects of SLR on net sediment movement are highly variable and controlled by the bathymetry of the reef and lagoon. A significant range of reef-lagoon bathymetry, and notably shallow and narrow reefs, appears to lead hydrodynamic conditions and beaches that are likely to be stable or even accrete under SLR. Loss of reef structural complexity, particularly on the reef flat, increases the chance of sediment transport away from beaches and offshore. Copyright © 2015 Elsevier Ltd. All rights reserved.

Decoupled diversification dynamics of feeding morphology following a major functional innovation in marine butterflyfishes.

PubMed

Konow, Nicolai; Price, Samantha; Abom, Richard; Bellwood, David; Wainwright, Peter

2017-08-16

The diversity of fishes on coral reefs is influenced by the evolution of feeding innovations. For instance, the evolution of an intramandibular jaw joint has aided shifts to corallivory in Chaetodon butterflyfishes following their Miocene colonization of coral reefs. Today, over half of all Chaetodon species consume coral, easily the largest concentration of corallivores in any reef fish family. In contrast with Chaetodon , other chaetodontids, including the long-jawed bannerfishes, remain less intimately associated with coral and mainly consume other invertebrate prey. Here, we test (i) if intramandibular joint (IMJ) evolution in Chaetodon has accelerated feeding morphological diversification, and (ii) if cranial and post-cranial traits were affected similarly. We measured 19 cranial functional morphological traits, gut length and body elongation for 33 Indo-Pacific species. Comparisons of Brownian motion rate parameters revealed that cranial diversification was about four times slower in Chaetodon butterflyfishes with the IMJ than in other chaetodontids. However, the rate of gut length evolution was significantly faster in Chaetodon , with no group-differences for body elongation. The contrasting patterns of cranial and post-cranial morphological evolution stress the importance of comprehensive datasets in ecomorphology. The IMJ appears to enhance coral feeding ability in Chaetodon and represents a design breakthrough that facilitates this trophic strategy. Meanwhile, variation in gut anatomy probably reflects diversity in how coral tissues are procured and assimilated. Bannerfishes, by contrast, retain a relatively unspecialized gut for processing invertebrate prey, but have evolved some of the most extreme cranial mechanical innovations among bony fishes for procuring elusive prey. © 2017 The Author(s).

Hydrocarbon potential of Morocco

DOE Office of Scientific and Technical Information (OSTI.GOV)

Achnin, H.; Nairn, A.E.M.

1988-08-01

Morocco lies at the junction of the African and Eurasian plates and carries a record of their movements since the end of the Precambrian. Four structural regions with basins and troughs can be identified: Saharan (Tarfaya-Ayoun and Tindouf basins); Anti-Atlas (Souss and Ouarzazate troughs and Boudnib basin); the Essaouria, Doukkala, Tadla, Missour, High Plateau, and Guercif basins; and Meseta and Rif (Rharb and Pre-Rif basins). The targets in the Tindouf basin are Paleozoic, Cambrian, Ordovician (clastics), Devonian (limestones), and Carboniferous reservoirs sourced primarily by Silurian shales. In the remaining basins, excluding the Rharb, the reservoirs are Triassic detritals, limestones atmore » the base of the Lias and Dogger, Malm detritals, and sandy horizons in the Cretaceous. In addition to the Silurian, potential source rocks include the Carboniferous and Permo-Carboniferous shales and clays; Jurassic shales, marls, and carbonates; and Cretaceous clays. In the Rharb basin, the objectives are sand lenses within the Miocene marls. The maturation level of the organic matter generally corresponds to oil and gas. The traps are stratigraphic (lenses and reefs) and structural (horsts and folds). The seals in the pre-Jurassic rocks are shales and evaporites; in the younger rocks, shales and marl. Hydrocarbon accumulations have been found in Paleozoic, Triassic, Liassic, Malm, and Miocene rocks.« less

Re-Os and S isotope evidence for the origin of Platreef mineralization (Bushveld Complex)

NASA Astrophysics Data System (ADS)

Yudovskaya, M.; Belousova, E.; Kinnaird, J.; Dubinina, E.; Grobler, D. F.; Pearson, N.

2017-10-01

The Bushveld Complex contains the largest platinum-group element (PGE) deposits of the world that are represented by persistent stratiform reefs highly enriched with PGE with respect to underlying and overlying rocks. New Re-Os isotope and elemental LA MC-ICPMS data on platinum-group minerals (PGM) from the mineralized reefs are presented with implications to correlation between the different segments of the Bushveld Complex and a role of superimposed processes at the reef formation. We analyzed laurite (RuS2), hollingworthite (RhAsS), sperrylite (PtAs2) and Pt-Fe alloys from the Merensky Reef, Pseudoreef and the PGE reef of the Platreef. The measured 187Os/188Os value for Platreef laurite is 0.1751 ± 0.0004 whereas the ratios for sperrylite and hollingworthite range to slightly higher values (0.1713-0.1818 and 0.1744-0.1835 respectively). The observed textures of the analyzed PGM, such as Pt-Fe symplectites in base metal sulfides (BMS), laurite inclusions in chromite and sperrylite rims around sulfide-silicate aggregates, are interpreted as features of primary magmatic crystallization whereas hollingworthite overgrowths and exsolutions in sperrylite are likely to have originated from later solid state transformation or metasomatic processes. The Platreef is a composite sill-like body in the northern limb correlative to the Critical Zone in terms of stratigraphic position, whole-rock geochemistry and isotope characteristics. The pristine magmatic character of sulfides and PGM in the stratiform reefs at the top of the Platreef strongly resembles the style of Merensky Reef mineralization. However, the basal part of the Platreef pyroxenitic sequence is variably contaminated and mineralized with a significant hydrothermal overprint. Sulfides from underlying Lower Zone peridotite yield δ34S values varying from +9‰ to +14.2‰ that are much higher than the values for the overlying Platreef and are a consequence of sulfur assimilation from sedimentary sulfates. The same homogeneous mantle-like S isotope compositions in the high-grade PGE reef of the Platreef and the Merensky Reef can be explained by enhanced S isotope exchange through the orthomagmatic process of sulfide upgrading. The similar values and the limited variations of the initial Os isotopic ratios of all PGMs in both reefs also support their magmatic crystallization and origin from a common source.

Characterising reef fish populations and habitats within and outside the US Virgin Islands Coral Reef National Monument: A lesson in marine protected area design

USGS Publications Warehouse

Monaco, Mark E.; Friedlander, A.M.; Caldow, Chris; Christensen, J.D.; Rogers, C.; Beets, J.; Miller, J.; Boulon, Rafe

2007-01-01

Marine protected areas are an important tool for management of marine ecosystems. Despite their utility, ecological design criteria are often not considered or feasible to implement when establishing protected areas. In 2001, the Virgin Islands Coral Reef National Monument (VICRNM) in St John, US Virgin Islands was established by Executive Order. The VICRNM prohibits almost all extractive uses. Surveys of habitat and fishes inside and outside of the VICRNM were conducted in 2002-2004. Areas outside the VICRNM had significantly more hard corals, greater habitat complexity, and greater richness, abundance and biomass of reef fishes than areas within the VICRNM. The administrative process used to delineate the boundaries of the VICRNM did not include a robust ecological characterisation of the area. Because of reduced habitat complexity within the VICRNM, the enhancement of the marine ecosystem may not be fully realised or increases in economically important reef fishes may take longer to detect. ?? 2007 The Authors. Journal compilation ?? 2007 Blackwell Publishing Ltd.

Christmas tree worms of Indo-Pacific coral reefs: untangling the Spirobranchus corniculatus (Grube, 1862) complex

NASA Astrophysics Data System (ADS)

Willette, Demian A.; Iñiguez, Abril R.; Kupriyanova, Elena K.; Starger, Craig J.; Varman, Tristan; Toha, Abdul Hamid; Maralit, Benedict A.; Barber, Paul H.

2015-09-01

Christmas tree worm is the common name of a group of colorful serpulid polychaetes from the genus Spirobranchus that are symbionts of hermatypic corals. As is increasingly common with reef-associated organisms, Spirobranchus is arranged as a complex of species with overlapping geographic ranges. Current species delimitations based largely on opercular morphology are problematic because of high intraspecific variation. Here, a multi-gene phylogeny of the Spirobranchus corniculatus complex, which tentatively includes S. corniculatus, S. cruciger, and S. gaymardi, sampled from the Coral Triangle, Australia, and Fiji, was reconstructed to test whether the complex includes three genetically distinct lineages identifiable by their opercula. Maximum-likelihood analyses of nuclear and mitochondrial markers revealed a single, monophyletic clade for the S. corniculatus complex. Furthermore, the genetic and morphological variation observed is not geographically based, indicating that the former S. corniculatus complex of three morphospecies is a single, morphologically variable species across the Central Indo-Pacific. Resolving the taxonomy of S. corniculatus presents novel opportunities to utilize this tentative bio-indicator species for monitoring reef health.

Calcification and Reef Building: Lessons from Recent History and The Holocene

NASA Astrophysics Data System (ADS)

Hubbard, D. K.

2016-02-01

Over the past four decades, coral abundance has declined while the rate of sea-level rise has accelerated. Calcification has also been negatively impacted due to changing ocean chemistry. As we consider the impact of these realities on the accretion rate of coral reefs and those who live near them, it is important to remember that the links between coral growth and reef accretion are complex. In the early 1980s a detailed carbonate budget was completed on the north coast of St. Croix in the US Virgin Islands. The study quantified coral cover, carbonate-production rates, bioerosion, sediment export and long-term reef accretion along two, shore-normal transects. A repeat of these measurements along one of the transects in 2014 revealed a 50% reduction in coral cover and a similar decline in the agents of bioerosion (primarily fish, sponges and urchins). When combined with modeling of increased sediment export as wave climate intensifies, these data suggest that Holocene reef-accretion rates will decline. To estimate the impact of this pattern on the ability of coral reefs to track rising sea level in the 21st century, Holocene accretion rates were compiled for 200 cores from 35 reefs representing all oceans. The accretion rates for over half of these were below the present rate of sea-level rise (3.3 mm/yr). Also, the rate of reef accretion was not strongly correlated with paleo-water depth. The declining carbonate budget from the US Virgin Islands (and elsewhere) suggests that many of the reefs that could have kept up with present-day sea-level rise can no longer do so. In addition, the lack of a consistent relationship between reef building and water depth suggests that biological factors (e.g., calcification and bioerosion) are insufficient to characterize reef building either in the past or the immediate future. The missing piece is the redistribution and export of sediment and rubble. While it is obvious that this will rise as storm intensity increases, we still need to do a better job of integrating what we know about the complex interplay between physical, biological and chemical controls of reef building.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazzullo, S.J.; Anderson-Underwood, K.E.; Burke, C.D.

Coral patch reefs are major components of Holocene platform carbonate facies systems in tropical and subtropical areas. The biotic composition, growth and relationship to sea level history, and diagenetic attributes of a representative Holocene patch reef ([open quotes]Elmer Reef[close quotes]) in the Mexico Rocks complex in northern Belize are described and compared to those of Holocene patch reefs in southern Belize. Elmer Reef has accumulated in shallow (2.5 m) water over the last 420 yr, under static sea level conditions. Rate of vertical construction is 0.3-0.5 m/100 yr, comparable to that of patch reefs in southern Belize. A pronounced coralmore » zonation exists across Elmer Reef, with Monastrea annularis dominating on its crest and Acropora cervicornis occurring on its windward and leeward flanks. The dominance of Montastrea on Elmer Reef is unlike that of patch reefs in southern Belize, in which this coral assumes only a subordinate role in reef growth relative to that of Acropora palmata. Elmer Reef locally is extensively biodegraded and marine, fibrous aragonite and some bladed high-magnesium calcite cements occur throughout the reef section, partially occluding corallites and interparticle pores in associated sands. Patch reefs in southern Belize have developed as catch-up and keep-up reefs in a transgressive setting. In contrast, the dominant mode of growth of Elmer Reef, and perhaps other patch reefs in Mexico Rocks, appears to be one of lateral rather than vertical accretion. This style of growth occurs in a static sea level setting where there is only limited accommodation space because of the shallowness of the water, and such reefs are referred to as [open quotes]expansion reefs[close quotes]. 39 refs., 8 figs., 2 tabs.« less

Global variations of large megathrust earthquake rupture characteristics

PubMed Central

Kanamori, Hiroo

2018-01-01

Despite the surge of great earthquakes along subduction zones over the last decade and advances in observations and analysis techniques, it remains unclear whether earthquake complexity is primarily controlled by persistent fault properties or by dynamics of the failure process. We introduce the radiated energy enhancement factor (REEF), given by the ratio of an event’s directly measured radiated energy to the calculated minimum radiated energy for a source with the same seismic moment and duration, to quantify the rupture complexity. The REEF measurements for 119 large [moment magnitude (Mw) 7.0 to 9.2] megathrust earthquakes distributed globally show marked systematic regional patterns, suggesting that the rupture complexity is strongly influenced by persistent geological factors. We characterize this as the existence of smooth and rough rupture patches with varying interpatch separation, along with failure dynamics producing triggering interactions that augment the regional influences on large events. We present an improved asperity scenario incorporating both effects and categorize global subduction zones and great earthquakes based on their REEF values and slip patterns. Giant earthquakes rupturing over several hundred kilometers can occur in regions with low-REEF patches and small interpatch spacing, such as for the 1960 Chile, 1964 Alaska, and 2011 Tohoku earthquakes, or in regions with high-REEF patches and large interpatch spacing as in the case for the 2004 Sumatra and 1906 Ecuador-Colombia earthquakes. Thus, combining seismic magnitude Mw and REEF, we provide a quantitative framework to better represent the span of rupture characteristics of great earthquakes and to understand global seismicity. PMID:29750186

Magmatic ore deposits in layered intrusions - Descriptive model for reef-type PGE and contact-type Cu-Ni-PGE deposits

USGS Publications Warehouse

Zientek, Michael L.

2012-01-01

Layered, ultramafic to mafic intrusions are uncommon in the geologic record, but host magmatic ore deposits containing most of the world's economic concentrations of platinum-group elements (PGE) (figs. 1 and 2). These deposits are mined primarily for their platinum, palladium, and rhodium contents (table 1). Magmatic ore deposits are derived from accumulations of crystals of metallic oxides, or immiscible sulfide, or oxide liquids that formed during the cooling and crystallization of magma, typically with mafic to ultramafic compositions. "PGE reefs" are stratabound PGE-enriched lode mineralization in mafic to ultramafic layered intrusions. The term "reef" is derived from Australian and South African literature for this style of mineralization and used to refer to (1) the rock layer that is mineralized and has distinctive texture or mineralogy (Naldrett, 2004), or (2) the PGE-enriched sulfide mineralization that occurs within the rock layer. For example, Viljoen (1999) broadly defined the Merensky Reef as "a mineralized zone within or closely associated with an unconformity surface in the ultramafic cumulate at the base of the Merensky Cyclic Unit." In this report, we will use the term PGE reef to refer to the PGE-enriched mineralization, not the host rock layer. Within a layered igneous intrusion, reef-type mineralization is laterally persistent along strike, extending for the length of the intrusion, typically tens to hundreds of kilometers. However, the mineralized interval is thin, generally centimeters to meters thick, relative to the stratigraphic thickness of layers in an intrusion that vary from hundreds to thousands of meters. PGE-enriched sulfide mineralization is also found near the contacts or margins of layered mafic to ultramafic intrusions (Iljina and Lee, 2005). This contact-type mineralization consists of disseminated to massive concentrations of iron-copper-nickel-PGE-enriched sulfide mineral concentrations in zones that can be tens to hundreds of meters thick. The modes and textures of the igneous rocks hosting the mineralization vary irregularly on the scale of centimeters to meters; autoliths and xenoliths are common. Mineralization occurs in the igneous intrusion and in the surrounding country rocks. Mineralization can be preferentially localized along contact with country rocks that are enriched in sulfur-, iron-, or CO2-bearing lithologies. Reef-type and contact-type deposits, in particular those in the Bushveld Complex, South Africa, are the world's primary source of platinum and rhodium (tables 2 and 3; fig. 2). Reef-type PGE deposits are mined only in the Bushveld Complex (Merensky Reef and UG2), the Stillwater Complex (J-M Reef), and the Great Dyke (Main Sulphide Layer). PGE-enriched contact-type deposits are only mined in the Bushveld Complex. The other deposits in tables 2 and 3 are undeveloped; some are still under exploration.

CHARACTERIZING CORAL CONDITION USING ESTIMATES OF THREE-DIMENSIONAL COLONY SURFACE AREA

EPA Science Inventory

Coral reefs provide shoreline protection, biological diversity, fishery harvets, and tourism, all values that stem from the physically-complex coral infrastructure. Stony corals (scleractinianss) construct and maintain the reef through deposition of calcium carbonate. Therefore...

The Antiquity of the Rhine River: Stratigraphic Coverage of the Dinotheriensande (Eppelsheim Formation) of the Mainz Basin (Germany)

PubMed Central

Böhme, Madelaine; Aiglstorfer, Manuela; Uhl, Dieter; Kullmer, Ottmar

2012-01-01

Background Mammalian fossils from the Eppelsheim Formation (Dinotheriensande) have been a benchmark for Neogene vertebrate palaeontology since 200 years. Worldwide famous sites like Eppelsheim serve as key localities for biochronologic, palaeobiologic, environmental, and mammal community studies. So far the formation is considered to be of early Late Miocene age (∼9.5 Ma, Vallesian), representing the oldest sediments of the Rhine River. The stratigraphic unity of the formation and of its fossil content was disputed at times, but persists unresolved. Principal Findings Here we investigate a new fossil sample from Sprendlingen, composed by over 300 mammalian specimens and silicified wood. The mammals comprise entirely Middle Miocene species, like cervids Dicrocerus elegans, Paradicrocerus elegantulus, and deinotheres Deinotherium bavaricum and D. levius. A stratigraphic evaluation of Miocene Central European deer and deinothere species proof the stratigraphic inhomogenity of the sample, and suggest late Middle Miocene (∼12.5 Ma) reworking of early Middle Miocene (∼15 Ma) sediments. This results agree with taxonomic and palaeoclimatic analysis of plant fossils from above and within the mammalian assemblage. Based on the new fossil sample and published data three biochronologic levels within the Dinotheriensand fauna can be differentiated, corresponding to early Middle Miocene (late Orleanian to early Astaracian), late Middle Miocene (late Astaracian), and early Late Miocene (Vallesian) ages. Conclusions/Significance This study documents complex faunal mixing of classical Dinotheriensand fauna, covering at least six million years, during a time of low subsidence in the Mainz Basin and shifts back the origination of the Rhine River by some five million years. Our results have severe implications for biostratigraphy and palaeobiology of the Middle to Late Miocene. They suggest that turnover events may be obliterated and challenge the proposed ‘supersaturated’ biodiversity, caused by Middle Miocene superstites, of Vallesian ecosystems in Central Europe. PMID:22615819

Reefs as cradles of evolution and sources of biodiversity in the Phanerozoic.

PubMed

Kiessling, Wolfgang; Simpson, Carl; Foote, Michael

2010-01-08

Large-scale biodiversity gradients among environments and habitats are usually attributed to a complex array of ecological and evolutionary factors. We tested the evolutionary component of such gradients by compiling the environments of the geologically oldest occurrences of marine genera and using sampling standardization to assess if originations tended to be clustered in particular environments. Shallow, tropical environments and carbonate substrates all tend to have harbored high origination rates. Diversity within these environments tended to be preferentially generated in reefs, probably because of their habitat complexity. Reefs were also prolific at exporting diversity to other environments, which might be a consequence of low-diversity habitats being more susceptible to invasions.

Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities.

PubMed

Fabricius, K E; De'ath, G; Noonan, S; Uthicke, S

2014-01-22

The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425-1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs.

Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities

PubMed Central

Fabricius, K. E.; De'ath, G.; Noonan, S.; Uthicke, S.

2014-01-01

The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425–1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs. PMID:24307670

Great Barrier Reef

NASA Image and Video Library

2017-12-08

Great Barrier Reef - August 8th, 1999 Description: What might be mistaken for dinosaur bones being unearthed at a paleontological dig are some of the individual reefs that make up the Great Barrier Reef, the world's largest tropical coral reef system. The reef stretches more than 2,000 kilometers (1,240 miles) along the coast of Queensland, Australia. It supports astoundingly complex and diverse communities of marine life and is the largest structure on the planet built by living organisms. Credit: USGS/NASA/Landsat 7 To learn more about the Landsat satellite go to: landsat.gsfc.nasa.gov/ NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Wave Dissipation on Low- to Super-Energy Coral Reefs

NASA Astrophysics Data System (ADS)

Harris, D. L.

2016-02-01

Coral reefs are valuable, complex and bio-diverse ecosystems and are also known to be one of the most effective barriers to swell events in coastal environments. Previous research has found coral reefs to be remarkably efficient in removing most of the wave energy during the initial breaking and transformation on the reef flats. The rate of dissipation is so rapid that coral reefs have been referred to as rougher than any known coastal barrier. The dissipation of wave energy across reef flats is crucial in maintaining the relatively low-energy conditions in the back reef and lagoonal environments providing vital protection to adjacent beach or coastal regions from cyclone and storm events. A shift in the regulation of wave energy by reef flats could have catastrophic consequences ecologically, socially, and economically. This study examined the dissipation of wave energy during two swell events in Tahiti and Moorea, French Polyesia. Field sites were chosen in varying degrees of exposure and geomorphology from low-energy protected sites (Tiahura, Moorea) to super-energy sites (Teahupo'o, Tahiti). Waves were measured during two moderate to large swell events in cross reef transects using short-term high-resolution pressure transducers. Wave conditions were found to be similar in all back reef locations despite the very different wave exposure at each reef site. However, wave conditions on the reef flats were different and mirrored the variation in wave exposure with depth over the reef flat the primary regulator of reef flat wave height. These results indicate that coral reef flats evolve morphodynamically with the wave climate, which creates coral reef geomorphologies capable of dissipating wave energy that results in similar back reef wave conditions regardless of the offshore wave climate.

New evidence for the barrier reef model, Permian Capitan Reef complex, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirkland, B.L.; Moore, C.H. Jr.

1990-05-01

Recent paleontologic and petrologic observations suggest that the Capitan Formation was deposited as an organic or ecologic reef that acted as an emergent barrier to incoming wave energy. In outcrops in the Guadalupe Mountains and within Carlsbad Caverns, massive reef boundstone contains a highly diverse assemblage of frame-building and binding organisms. In modern reefs, diversity among frame builders decreases dramatically with depth. Marine cement is abundant in reef boundstone, but limited in back-reef grainstone and packstone. This cementation pattern is similar to that observed in modern emergent barrier reef systems. Based on comparison with modern analogs, these dasycladrominated back-reef sedimentsmore » and their associated biota are indicative of shallow, hypersaline conditions. Few of these dasyclads exhibit broken or abraded segments and some thallus sections are still articulated suggesting that low-energy, hypersaline conditions occurred immediately shelfward of the reef. In addition, large-scale topographic features, such as possible spur and groove structures between Walnut Canyon and Rattlesnake Canyon, and facies geometries, such as the reef to shelf transition, resemble those found in modern shallow-water reefs. The organisms that formed the Capitan Reef appear to have lived in, and responded to, physical and chemical conditions similar to those that control the geometry of modern shallow-water reefs. Like their modern counterparts, they seem to have strongly influenced adjacent environments. In light of this evidence, consideration should be given to either modifying or abandoning the marginal mound model in favor of the originally proposed barrier reef model.« less

Sedimentary response to orogenic exhumation in the northern rocky mountain basin and range province, flint creek basin, west-central Montana

USGS Publications Warehouse

Portner, R.A.; Hendrix, M.S.; Stalker, J.C.; Miggins, D.P.; Sheriff, S.D.

2011-01-01

Middle Eocene through Upper Miocene sedimentary and volcanic rocks of the Flint Creek basin in western Montana accumulated during a period of significant paleoclimatic change and extension across the northern Rocky Mountain Basin and Range province. Gravity modelling, borehole data, and geologic mapping from the Flint Creek basin indicate that subsidence was focused along an extensionally reactivated Sevier thrust fault, which accommodated up to 800 m of basin fill while relaying stress between the dextral transtensional Lewis and Clark lineament to the north and the Anaconda core complex to the south. Northwesterly paleocurrent indicators, foliated metamorphic lithics, 64 Ma (40Ar/39Ar) muscovite grains, and 76 Ma (U-Pb) zircons in a ca. 27 Ma arkosic sandstone are consistent with Oligocene exhumation and erosion of the Anaconda core complex. The core complex and volcanic and magmatic rocks in its hangingwall created an important drainage divide during the Paleogene shedding detritus to the NNW and ESE. Following a major period of Early Miocene tectonism and erosion, regional drainage networks were reorganized such that paleoflow in the Flint Creek basin flowed east into an internally drained saline lake system. Renewed tectonism during Middle to Late Miocene time reestablished a west-directed drainage that is recorded by fluvial strata within a Late Miocene paleovalley. These tectonic reorganizations and associated drainage divide explain observed discrepancies in provenance studies across the province. Regional correlation of unconformities and lithofacies mapping in the Flint Creek basin suggest that localized tectonism and relative base level fluctuations controlled lithostratigraphic architecture.

Extensive metazoan reefs from the Ediacaran Nama Group, Namibia: the rise of benthic suspension feeding.

PubMed

Wood, R; Curtis, A

2015-03-01

We describe new, ecologically complex reef types from the Ediacaran Nama Group, Namibia, dated at ~548 million years ago (Ma), where the earliest known skeletal metazoans, Cloudina riemkeae and Namacalathus, formed extensive reefs up to 20 m in height and width. C. riemkeae formed densely aggregating assemblages associated with microbialite and thrombolite, each from 30 to 100 mm high, which successively colonised former generations to create stacked laminar or columnar reef frameworks. C. riemkeae individuals show budding, multiple, radiating attachment sites and cementation between individuals. Isolated Namacalathus either intergrew with C. riemkeae or formed dense, monospecific aggregations succeeding C. riemkeae frameworks, providing a potential example of environmentally mediated ecological succession. Cloudina and Namacalathus also grow cryptically, either as pendent aggregations from laminar crypt ceilings in microbial framework reefs or as clusters associated with thrombolite attached to neptunian dyke walls. These reefs are notable for their size, exceeding that of the succeeding Lower Cambrian archaeocyath-microbial communities. The repeated colonisation shown by C. riemkeae of former assemblages implies philopatric larval aggregation to colonise limited favourable substrates. As such, not only were skeletal metazoans more important contributors to reef building in the Ediacaran, but there were also more variable reef types with more complex ecologies, than previously thought. Such an abundance of inferred suspension feeders with biomineralised skeletons indicates the efficient exploitation of new resources, more active carbon removal with a strengthened energy flow between planktic and benthic realms, and the rise of biological control over benthic carbonate production. These mark the prelude to the Cambrian Explosion and the modernisation of the global carbon cycle. © 2014 John Wiley & Sons Ltd.

Using novel acoustic and visual mapping tools to predict the small-scale spatial distribution of live biogenic reef framework in cold-water coral habitats

NASA Astrophysics Data System (ADS)

De Clippele, L. H.; Gafeira, J.; Robert, K.; Hennige, S.; Lavaleye, M. S.; Duineveld, G. C. A.; Huvenne, V. A. I.; Roberts, J. M.

2017-03-01

Cold-water corals form substantial biogenic habitats on continental shelves and in deep-sea areas with topographic highs, such as banks and seamounts. In the Atlantic, many reef and mound complexes are engineered by Lophelia pertusa, the dominant framework-forming coral. In this study, a variety of mapping approaches were used at a range of scales to map the distribution of both cold-water coral habitats and individual coral colonies at the Mingulay Reef Complex (west Scotland). The new ArcGIS-based British Geological Survey (BGS) seabed mapping toolbox semi-automatically delineated over 500 Lophelia reef `mini-mounds' from bathymetry data with 2-m resolution. The morphometric and acoustic characteristics of the mini-mounds were also automatically quantified and captured using this toolbox. Coral presence data were derived from high-definition remotely operated vehicle (ROV) records and high-resolution microbathymetry collected by a ROV-mounted multibeam echosounder. With a resolution of 0.35 × 0.35 m, the microbathymetry covers 0.6 km2 in the centre of the study area and allowed identification of individual live coral colonies in acoustic data for the first time. Maximum water depth, maximum rugosity, mean rugosity, bathymetric positioning index and maximum current speed were identified as the environmental variables that contributed most to the prediction of live coral presence. These variables were used to create a predictive map of the likelihood of presence of live cold-water coral colonies in the area of the Mingulay Reef Complex covered by the 2-m resolution data set. Predictive maps of live corals across the reef will be especially valuable for future long-term monitoring surveys, including those needed to understand the impacts of global climate change. This is the first study using the newly developed BGS seabed mapping toolbox and an ROV-based microbathymetric grid to explore the environmental variables that control coral growth on cold-water coral reefs.

Chemical data and variation diagrams of igneous rocks from the Timber Mountain-Oasis Valley Caldera Complex, southern Nevada

USGS Publications Warehouse

Quinlivan, W.D.; Byers, F.M.

1977-01-01

Silica variation diagrams presented here are based on 162 chemical analyses of tuffs, lavas, and intrusives, representative of volcanic centers of the Timber Mountain-Oasis Valley caldera complex and cogenetic rocks of the Silent Canyon ca1dera. Most of the volcanic units sampled are shown on the U.S. Geological Survey geologic map of the Timber Mountain caldera area (I-891) and are described in U.S. Geological Survey Professional Paper 919. Early effusives of the complex, although slightly altered, are probably chemically, and petrographically, more like the calc-alkalic Fraction Tuff (Miocene) of the northern Nellis Air Force Base Bombing and Gunnery Range to the north, whereas effusives of later Miocene age, such as the Paintbrush and Timber Mountain Tuffs, are alkali-calcic.

Use of riverine through reef habitat systems by dog snapper ( Lutjanus jocu ) in eastern Brazil

NASA Astrophysics Data System (ADS)

Moura, Rodrigo L.; Francini-Filho, Ronaldo B.; Chaves, Eduardo M.; Minte-Vera, Carolina V.; Lindeman, Kenyon C.

2011-11-01

The early life history of Western Atlantic snappers from the Southern hemisphere is largely unknown. Habitat use of different life stages (i.e. size categories) of the dog snapper ( Lutjanus jocu) was examined across the largest South Atlantic reef-estuarine complex (Abrolhos Shelf, Brazil, 16-19° S). Visual surveys were conducted in different habitats across the shelf (estuary, inner-shelf reefs and mid-shelf reefs). Lutjanus jocu showed higher densities on inner-shelf habitats, with a clear increase in fish size across the shelf. Individuals <7 cm were associated with both the estuary (mangrove and rocky habitats) and inner-shelf reefs (particularly shallow fore-reefs and tide pools). Individuals ranging 10-30 cm were broadly distributed, but consistently more abundant on inner-shelf reefs. Individuals between 30 and 40 cm were more common on mid-shelf reefs, while individuals >40 cm were recorded only on mid-shelf reefs. Literature data indicate that individuals ranging 70-80 cm are common on deep offshore reefs. This pattern suggests that the dog snapper performs ontogenetic cross-shelf migrations. Protecting portions of the different habitats used by the dog snapper during its post-settlement life cycle is highlighted as an important conservation and management measure.

Towards an Ontology for Reef Islands

NASA Astrophysics Data System (ADS)

Duce, Stephanie

Reef islands are complex, dynamic and vulnerable environments with a diverse range of stake holders. Communication and data sharing between these different groups of stake holders is often difficult. An ontology for the reef island domain would improve the understanding of reef island geomorphology and improve communication between stake holders as well as forming a platform from which to move towards interoperability and the application of Information Technology to forecast and monitor these environments. This paper develops a small, prototypical reef island domain ontology, based on informal, natural language relations, aligned to the DOLCE upper-level ontology, for 20 fundamental terms within the domain. A subset of these terms and their relations are discussed in detail. This approach reveals and discusses challenges which must be overcome in the creation of a reef island domain ontology and which could be relevant to other ontologies in dynamic geospatial domains.

Diagenesis and evolution of microporosity of Middle-Upper Devonian Kee Scarp reefs, Norman Wells, Northwest Territories, Canada: Petrographic and chemical evidence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Aasm, I.S.; Azmy, K.K.

The Middle-Upper Devonian Kee Scarp reef complexes of Norman Wells, Northwest Territories, Canada, are oil-producing, stromatoporoid-dominated carbonates. Episodic increases in the rate of sea level rise produced multiple cycles of reef growth that exhibit backstepping characteristics. These carbonates, composed of invariably altered limestones, have original interskeletal, intraskeletal, and intergranular porosity, mostly occluded by nonferroan, dull luminescent cements. Secondary porosity, represented by micropores of various types, developed during diagenesis by aggrading neomorphism and dissolution. The micropores represent the main reservoir porosity in the Kee Scarp limestone. Petrographic, chemical, and isotopic studies of Kee Scarp reef components reveal a complex diagenetic historymore » involving marine fluids modified by increasing water/rock interaction and burial. Neomorphic stabilization of skeletal components caused further depletion in {gamma}{sup 18}O but very little change in {gamma}{sup 13}C, an argument for modification of the original marine fluids with increasing burial. Variations in magnitude of water/rock interaction with depth, facies changes, and porosity modifications probably exerted some control on fractionation and distribution of stable isotopes and trace elements in reef components.« less

Modelling reef zonation in the Greater St Lucia Wetland Park, South Africa

NASA Astrophysics Data System (ADS)

Schleyer, Michael H.; Celliers, Louis

2005-05-01

East Africa has a rich coral fauna that extends to Maputaland in KwaZulu-Natal, South Africa. At this latitude, considered high and marginal for coral distribution and development, they form a veneer on limited, late Pleistocene reefs rather than forming the accretive, aragonite structures known as coral reefs. It is thus more appropriate to refer to them in this region as coral communities, the environment being rendered marginal for their development by reduced temperatures, light and aragonite saturation state. Subsequent to their discovery, the reefs were afforded protection within two Marine Protected Areas (the St Lucia and Maputaland Marine Reserves). They are found primarily within three reef complexes, with only the central complex being readily accessible to the public for ecotourism at present. With the creation of the Greater St Lucia Wetland Park, a World Heritage Site, and the expectation of an accompanying increase in ecotourism, the status quo seems set to change. The reefs are thus the current focus of a modelling initiative to provide decision support in their management. This paper examines the unique nature of the South African communities, their vulnerability and importance in the regional and global context, and, using representative data from the model, how an anticipated increase in their use could affect their sustainability. The case for scientifically based zonation for their use is presented.

Early Miocene depositional environments in the northern margin of the Mediterranean, southwestern Anatolia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yavuz, H.H.; Oercen, S.

1988-08-01

The continental and shallow marine clastics and carbonates exposed around the towns of Kale and Acipayam in southwestern Anatolia were investigated to interpret the depositional environments in the northern margin of the Mediterranean in terms of lithofacies and biozones. These deposits include Miogypsina intermedia and M. irregularis, indicating Burdigalian age when correlated with the same species in the different parts of the Tethys Sea and Indian-Pacific Oceans. The clastic lower part of the succession is characterized by sheet flow and braided-stream deposits of an alluvial-fan/fan-delta complex. Marine carbonates overlie these deposits, but in some places a transgressive lag deposit liesmore » between the unconformity surface and the carbonates. The lag deposit unit corresponds to the Gastropoda biozone, including Ostrea, Terebralia, and Pecten. Four carbonate facies are recognized: (1) Clayey limestones with ahermatypic corals, ostracods, macrofossils, and foraminifers. This facies corresponds to the Textularia-Rotalia biozone. (2) Packstones and grainstones with abundant nearshore and some offshore foraminifers, corresponding to the Miliolidae biozone. (3) Packstones and wackestones with offshore foraminifers. This facies includes the Miogypsina irregularis-Miogypsina intermedia biozone. (4) Boundstones and very poorly sorted reef-talus conglomerates including hermatypic corals, foraminifers, and binding foraminifers. This facies is the coral biozone. These sediments define the northern extent of the Tethys Sea in the investigated area during the Burdigalian. They were deposited in a shallow carbonate platform at the southern margin of the Anatolian mainland, which had a steep coast characterized by an alluvial-fan/fan-delta complex.« less

Image Fusion Applied to Satellite Imagery for the Improved Mapping and Monitoring of Coral Reefs: a Proposal

NASA Astrophysics Data System (ADS)

Gholoum, M.; Bruce, D.; Hazeam, S. Al

2012-07-01

A coral reef ecosystem, one of the most complex marine environmental systems on the planet, is defined as biologically diverse and immense. It plays an important role in maintaining a vast biological diversity for future generations and functions as an essential spawning, nursery, breeding and feeding ground for many kinds of marine species. In addition, coral reef ecosystems provide valuable benefits such as fisheries, ecological goods and services and recreational activities to many communities. However, this valuable resource is highly threatened by a number of environmental changes and anthropogenic impacts that can lead to reduced coral growth and production, mass coral mortality and loss of coral diversity. With the growth of these threats on coral reef ecosystems, there is a strong management need for mapping and monitoring of coral reef ecosystems. Remote sensing technology can be a valuable tool for mapping and monitoring of these ecosystems. However, the diversity and complexity of coral reef ecosystems, the resolution capabilities of satellite sensors and the low reflectivity of shallow water increases the difficulties to identify and classify its features. This paper reviews the methods used in mapping and monitoring coral reef ecosystems. In addition, this paper proposes improved methods for mapping and monitoring coral reef ecosystems based on image fusion techniques. This image fusion techniques will be applied to satellite images exhibiting high spatial and low to medium spectral resolution with images exhibiting low spatial and high spectral resolution. Furthermore, a new method will be developed to fuse hyperspectral imagery with multispectral imagery. The fused image will have a large number of spectral bands and it will have all pairs of corresponding spatial objects. This will potentially help to accurately classify the image data. Accuracy assessment use ground truth will be performed for the selected methods to determine the quality of the information derived from image classification. The research will be applied to the Kuwait's southern coral reefs: Kubbar and Um Al-Maradim.

Habitat, Fauna, and Conservation of Florida's Deep-Water Coral Reefs

NASA Astrophysics Data System (ADS)

Reed, J. K.; Pomponi, S. A.; Messing, C. G.; Brooke, S.

2008-05-01

Various types of deep-water coral habitats are common off the southeastern United States from the Blake Plateau through the Straits of Florida to the eastern Gulf of Mexico. Expeditions in the past decade with the Johnson-Sea- Link manned submersibles, ROVs, and AUVs have discovered, mapped and compiled data on the status, distribution, habitat, and biodiversity for many of these relatively unknown deep-sea coral ecosystems. We have discovered over three hundred, high relief (15-152-m tall) coral mounds (depth 700-800 m) along the length of eastern Florida (700 km). The north Florida sites are rocky lithoherms, whereas the southern sites are primarily classic coral bioherms, capped with dense 1-2 m tall thickets of Lophelia pertusa and Enallopsammia profunda. Off southeastern Florida, the Miami Terrace escarpment (depth 300-600 m) extends nearly 150 km as a steep, rocky slope of Miocene-age phosphoritic limestone, which provides habitat for a rich biodiversity of fish and benthic invertebrates. Off the Florida Keys, the Pourtalès Terrace (depth 200- 460 m) has extensive high-relief bioherms and numerous deep-water sinkholes to depths of 250-610 m and diameters up to 800 m. The dominant, deep-water, colonial scleractinian corals in this region include Oculina varicosa, L. pertusa, E. profunda, Madrepora oculata, and Solenosmilia variabilis. Other coral species include hydrozoans (Stylasteridae), bamboo octocorals (Isididae), numerous other gorgonians, and black corals (Antipatharia). These structure-forming taxa provide habitat and living space for a relatively unknown but biologically rich and diverse community of crustaceans, mollusks, echinoderms, polychaete and sipunculan worms, and associated fishes. We have identified 142 taxa of benthic macro-invertebrates, including 66 Porifera and 57 Cnidaria. Nearly 100 species of fish have been identified to date in association with these deep-water coral habitats. Paull et al. (2000) estimated that over 40,000 individual deep-water lithoherms may occur on the Blake Plateau and Straits of Florida, perhaps exceeding the areal extent of all the shallow-water reefs of the southeastern U.S. Our research program has provided data on the status of knowledge concerning these deep-reef habitats to the South Atlantic Fishery Management Council (SAFMC). Currently pending is a proposal by the SAFMC for a deep- water coral Habitat Area of Particular Concern (HAPC) that would extend from North Carolina to south Florida (78,888 km2) to protect these diverse and irreplaceable resources from destructive fishing activities such as bottom trawling. Deep-water reefs worldwide have been severely impacted by bottom trawling, including the deep-water Oculina coral reefs off central eastern Florida, which are structurally similar to the Lophelia reefs. Over a 30-year period, up to 99% of unprotected portions of the Oculina reefs were destroyed by rock shrimp trawling, whereas reefs designated as the Oculina HAPC in 1984 were protected from trawling and long-lines and are still relatively healthy. Numerous fisheries may target the deep-water Lophelia reef habitat including royal red shrimp, golden crab, and various fin fish.

Possible modes of coral-reef development at Molokai, Hawaii, inferred from seismic-reflection profiling

USGS Publications Warehouse

Barnhardt, W.A.; Richmond, B.M.; Grossman, E.E.; Hart, P.

2005-01-01

High-resolution, seismic-reflection data elucidate the late Quaternary development of the largest coral-reef complex in the main Hawaiian Islands. Six acoustic facies were identified from reflection characteristics and lithosome geometry. An extensive, buried platform with uniformly low relief was traced beneath fore-reef and marginal shelf environments. This highly reflective surface dips gently seaward to ???130 m depth and locally crops out on the seafloor. It probably represents a wave-cut platform or ancient reef flat. We propose alternative evolutionary models, in which sea-level changes have modulated the development of reef systems, to explain the observed stratigraphic relationships. The primary difference between the models is the origin of the underlying antecedent surface, which arguably could have formed during either regression/lowstand or subsequent transgression. 

Episodic Cenozoic volcanism and tectonism in the Andes of Peru

USGS Publications Warehouse

Noble, D.C.; McKee, E.H.; Farrar, E.; Petersen, U.

1974-01-01

Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise. ?? 1974.

Diseases and partial mortality in Montastraea annularis species complex in reefs with differing environmental conditions (NW Caribbean and Gulf of Mexico).

PubMed

Jordán-Dahlgren, Eric; Maldonado, Miguel Angel; Rodríguez-Martínez, Rosa Elisa

2005-01-25

We documented the prevalence of diseases, syndromes and partial mortality in colonies of the Montastraea annularis species complex on 3 reefs, and tested the assumption that a higher prevalence of these parameters occurs when reefs are closer to point-sources of pollution. One reef was isolated from the impact of local factors with the exception of fishing, 1 potentially influenced by local industrial pollutants, and 1 influenced by local urban pollution. Two reefs were surveyed in 1996 and again in 2001 and 1 in 1998 and again in 2001. In 2001, colonies on all reefs had a high prevalence of the yellow-band syndrome and a relatively high degree of recent partial mortality, while the prevalence of black-band and white-plague diseases was low although a new sign, that we named the thin dark line, had relatively high prevalence in all reefs. As no direct relationship was found between disease prevalence and local environmental quality, our results open the possibility that regional and/or global factors may already be playing an important role in the prevalence of coral disease in the Caribbean, and contradict the theory that coral disease prevalence is primarily related to local environmental degradation. Reasons that may partially explain these findings are the high level of potential pathogen connectivity within the Caribbean as a result of its circulation patterns coupled to the large land-derived pollutants and pathogens input into this Mediterranean sea, together with the surface water warming effects which stress corals and enhance pathogen activity.

Relationships between reef fish communities and remotely sensed rugosity measurements in Biscayne National Park, Florida, USA

USGS Publications Warehouse

Kuffner, Ilsa B.; Brock, John C.; Grober-Dunsmore, Rikki; Bonito, Victor E.; Hickey, T. Donald; Wright, C. Wayne

2007-01-01

The realization that coral reef ecosystem management must occur across multiple spatial scales and habitat types has led scientists and resource managers to seek variables that are easily measured over large areas and correlate well with reef resources. Here we investigate the utility of new technology in airborne laser surveying (NASA Experimental Advanced Airborne Research Lidar (EAARL)) in assessing topographical complexity (rugosity) to predict reef fish community structure on shallow (n = 10–13 per reef). Rugosity at each station was assessed in situ by divers using the traditional chain-transect method (10-m scale), and remotely using the EAARL submarine topography data at multiple spatial scales (2, 5, and 10 m). The rugosity and biological datasets were analyzed together to elucidate the predictive power of EAARL rugosity in describing the variance in reef fish community variables and to assess the correlation between chain-transect and EAARL rugosity. EAARL rugosity was not well correlated with chain-transect rugosity, or with species richness of fishes (although statistically significant, the amount of variance explained by the model was very low). Variance in reef fish community attributes was better explained in reef-by-reef variability than by physical variables. However, once the reef-by-reef variability was taken into account in a two-way analysis of variance, the importance of rugosity could be seen on individual reefs. Fish species richness and abundance were statistically higher at high rugosity stations compared to medium and low rugosity stations, as predicted by prior ecological research. The EAARL shows promise as an important mapping tool for reef resource managers as they strive to inventory and protect coral reef resources.

Last interglacial reef growth beneath Belize barrier and isolated platform reefs

USGS Publications Warehouse

Gischler, Eberhard; Lomando, Anthony J.; Hudson, J. Harold; Holmes, Charles W.

2000-01-01

We report the first radiometric dates (thermal-ionization mass spectrometry) from late Pleistocene reef deposits from offshore Belize, the location of the largest modern reef complex in the Atlantic Ocean. The results presented here can be used to explain significant differences in bathymetry, sedimentary facies, and reef development of this major reef area, and the results are significant because they contribute to the knowledge of the regional geology of the eastern Yucatán. The previously held concept of a neotectonically stable eastern Yucatán is challenged. The dates indicate that Pleistocene reefs and shallow-water limestones, which form the basement of modern reefs in the area, accumulated ca. 125–130 ka. Significant differences in elevation of the samples relative to present sea level (>10 m) have several possible causes. Differential subsidence along a series of continental margin fault blocks in combination with variation in karstification are probably the prime causes. Differential subsidence is presumably related to initial extension and later left-lateral movements along the adjacent active boundary between the North American and Caribbean plates. Increasing dissolution toward the south during Pleistocene sea-level lowstands is probably a consequence of higher precipitation rates in mountainous southern Belize.

Using virtual reality to estimate aesthetic values of coral reefs

PubMed Central

Clifford, Sam; Caley, M. Julian; Pearse, Alan R.; Brown, Ross; James, Allan; Christensen, Bryce; Bednarz, Tomasz; Anthony, Ken; González-Rivero, Manuel; Mengersen, Kerrie; Peterson, Erin E.

2018-01-01

Aesthetic value, or beauty, is important to the relationship between humans and natural environments and is, therefore, a fundamental socio-economic attribute of conservation alongside other ecosystem services. However, beauty is difficult to quantify and is not estimated well using traditional approaches to monitoring coral-reef aesthetics. To improve the estimation of ecosystem aesthetic values, we developed and implemented a novel framework used to quantify features of coral-reef aesthetics based on people's perceptions of beauty. Three observer groups with different experience to reef environments (Marine Scientist, Experienced Diver and Citizen) were virtually immersed in Australian's Great Barrier Reef (GBR) using 360° images. Perceptions of beauty and observations were used to assess the importance of eight potential attributes of reef-aesthetic value. Among these, heterogeneity, defined by structural complexity and colour diversity, was positively associated with coral-reef-aesthetic values. There were no group-level differences in the way the observer groups perceived reef aesthetics suggesting that past experiences with coral reefs do not necessarily influence the perception of beauty by the observer. The framework developed here provides a generic tool to help identify indicators of aesthetic value applicable to a wide variety of natural systems. The ability to estimate aesthetic values robustly adds an important dimension to the holistic conservation of the GBR, coral reefs worldwide and other natural ecosystems. PMID:29765676

Using virtual reality to estimate aesthetic values of coral reefs.

PubMed

Vercelloni, Julie; Clifford, Sam; Caley, M Julian; Pearse, Alan R; Brown, Ross; James, Allan; Christensen, Bryce; Bednarz, Tomasz; Anthony, Ken; González-Rivero, Manuel; Mengersen, Kerrie; Peterson, Erin E

2018-04-01

Aesthetic value, or beauty, is important to the relationship between humans and natural environments and is, therefore, a fundamental socio-economic attribute of conservation alongside other ecosystem services. However, beauty is difficult to quantify and is not estimated well using traditional approaches to monitoring coral-reef aesthetics. To improve the estimation of ecosystem aesthetic values, we developed and implemented a novel framework used to quantify features of coral-reef aesthetics based on people's perceptions of beauty. Three observer groups with different experience to reef environments (Marine Scientist, Experienced Diver and Citizen) were virtually immersed in Australian's Great Barrier Reef (GBR) using 360° images. Perceptions of beauty and observations were used to assess the importance of eight potential attributes of reef-aesthetic value. Among these, heterogeneity, defined by structural complexity and colour diversity, was positively associated with coral-reef-aesthetic values. There were no group-level differences in the way the observer groups perceived reef aesthetics suggesting that past experiences with coral reefs do not necessarily influence the perception of beauty by the observer. The framework developed here provides a generic tool to help identify indicators of aesthetic value applicable to a wide variety of natural systems. The ability to estimate aesthetic values robustly adds an important dimension to the holistic conservation of the GBR, coral reefs worldwide and other natural ecosystems.

Molecules and fossils reveal punctuated diversification in Caribbean “faviid” corals

PubMed Central

2012-01-01

Background Even with well-known sampling biases, the fossil record is key to understanding macro-evolutionary patterns. During the Miocene to Pleistocene in the Caribbean Sea, the fossil record of scleractinian corals shows a remarkable period of rapid diversification followed by massive extinction. Here we combine a time-calibrated molecular phylogeny based on three nuclear introns with an updated fossil stratigraphy to examine patterns of radiation and extinction in Caribbean corals within the traditional family Faviidae. Results Concatenated phylogenetic analysis showed most species of Caribbean faviids were monophyletic, with the exception of two Manicina species. The time-calibrated tree revealed the stem group originated around the closure of the Tethys Sea (17.0 Ma), while the genus Manicina diversified during the Late Miocene (8.20 Ma), when increased sedimentation and productivity may have favored free-living, heterotrophic species. Reef and shallow water specialists, represented by Diploria and Favia, originate at the beginning of the Pliocene (5 – 6 Ma) as the Isthmus of Panama shoaled and regional productivity declined. Conclusions Later origination of the stem group than predicted from the fossil record corroborates the hypothesis of morphological convergence in Diploria and Favia genera. Our data support the rapid evolution of morphological and life-history traits among faviid corals that can be linked to Mio-Pliocene environmental changes. PMID:22831179

Estimating Surface Area of Sponges and Marine Gorgonians as Indicators of Habitat Availability on Caribbean Coral Reefs

EPA Science Inventory

Surface area and topographical complexity are fundamental attributes of shallow tropical coral reefs and can be used to estimate habitat for fish and invertebrates. This study presents empirical methods for estimating surface area provided by sponges and gorgonians in the Central...

Calcareous nannofossil biostratigraphy and geochronology of Neogene trench-slope cover sediments in the south Boso Peninsula, central Japan: Implications for the development of a shallow accretionary complex

NASA Astrophysics Data System (ADS)

Chiyonobu, Shun; Yamamoto, Yuzuru; Saito, Saneatsu

2017-07-01

The geological structure and calcareous nannofossil biostratigraphy of the Middle to Late Miocene trench-slope succession in the southern Boso Peninsula, central Japan, were examined to obtain chronological constraints on the accretion and formation of the trench-slope architecture. As a result, trench-slope cover sediments (Kinone and Amatsu Formations) are clearly distinguishable from the Early Miocene Hota accretionary complex (Hota Group). The Hota accretionary complex was deposited below the carbonate compensation depth (CCD) and was affected by intense shearing, forming an east-west trending and south-verging fold and thrust belt. In contrast, the trench-slope cover sediments basically have a homoclinal dip, except at the northern rim where they are bounded by fault contact. They contain many species of calcareous nannofossils and foraminifers, which are indicative of their depositional environment above the CCD, and they show shallowing-upward sedimentary structures. Biostratigraphy revealed that the depositional age of the trench-slope sediments is ca. 15-5.5 Ma, suggesting that there is an approximately 2 myr hiatus beween the Miura Group and the underlying accretionary prism. Based on these results, the age of accretion of the Hota Group is inferred to be between ca. 17-15 Ma, and the group is covered by trench-slope sediments overlain on it after ca. 15 Ma. The timing of accretion and the age of the trench-slope basin tend to be younger southward of the Boso Peninsula. The accretionary system of the Boso Peninsula apparently developed in two stages, in the Middle Miocene and in the Late Miocene to Pliocene.

Re-creating missing population baselines for Pacific reef sharks.

PubMed

Nadon, Marc O; Baum, Julia K; Williams, Ivor D; McPherson, Jana M; Zgliczynski, Brian J; Richards, Benjamin L; Schroeder, Robert E; Brainard, Russell E

2012-06-01

Sharks and other large predators are scarce on most coral reefs, but studies of their historical ecology provide qualitative evidence that predators were once numerous in these ecosystems. Quantifying density of sharks in the absence of humans (baseline) is, however, hindered by a paucity of pertinent time-series data. Recently researchers have used underwater visual surveys, primarily of limited spatial extent or nonstandard design, to infer negative associations between reef shark abundance and human populations. We analyzed data from 1607 towed-diver surveys (>1 ha transects surveyed by observers towed behind a boat) conducted at 46 reefs in the central-western Pacific Ocean, reefs that included some of the world's most pristine coral reefs. Estimates of shark density from towed-diver surveys were substantially lower (<10%) than published estimates from surveys along small transects (<0.02 ha), which is not consistent with inverted biomass pyramids (predator biomass greater than prey biomass) reported by other researchers for pristine reefs. We examined the relation between the density of reef sharks observed in towed-diver surveys and human population in models that accounted for the influence of oceanic primary productivity, sea surface temperature, reef area, and reef physical complexity. We used these models to estimate the density of sharks in the absence of humans. Densities of gray reef sharks (Carcharhinus amblyrhynchos), whitetip reef sharks (Triaenodon obesus), and the group "all reef sharks" increased substantially as human population decreased and as primary productivity and minimum sea surface temperature (or reef area, which was highly correlated with temperature) increased. Simulated baseline densities of reef sharks under the absence of humans were 1.1-2.4/ha for the main Hawaiian Islands, 1.2-2.4/ha for inhabited islands of American Samoa, and 0.9-2.1/ha for inhabited islands in the Mariana Archipelago, which suggests that density of reef sharks has declined to 3-10% of baseline levels in these areas. ©2012 Society for Conservation Biology No claim to original US government works.

Evidence of offshore lake trout reproduction in Lake Huron

USGS Publications Warehouse

DeSorcie, Timothy J.; Bowen, Charles A.

2003-01-01

Six Fathom Bank-Yankee Reef, an offshore reef complex, was an historically important spawning area believed to represent some of the best habitat for the rehabilitation of lake trout Salvelinus namaycush in Lake Huron. Since 1986, lake trout have been stocked on these offshore reefs to reestablish self-sustaining populations. We sampled with beam trawls to determine the abundance of naturally reproduced age-0 lake trout on these offshore reefs during May-July in 1994-1998 and 2000-2002. In total, 123 naturally reproduced lake trout fry were caught at Six Fathom Bank, and 2 naturally reproduced lake trout fry were caught at nearby Yankee Reef. Our findings suggest that this region of Lake Huron contains suitable habitat for lake trout spawning and offers hope that lake trout rehabilitation can be achieved in the main basin of Lake Huron.

Differential effects of habitat complexity, predators and competitors on abundance of juvenile and adult coral reef fishes.

PubMed

Almany, Glenn R

2004-09-01

Greater structural complexity is often associated with greater abundance and diversity, perhaps because high complexity habitats reduce predation and competition. Using 16 spatially isolated live-coral reefs in the Bahamas, I examined how abundance of juvenile (recruit) and adult (non-recruit) fishes was affected by two factors: (1) structural habitat complexity and (2) the presence of predators and interference competitors. Manipulating the abundance of low and high complexity corals created two levels of habitat complexity, which was cross-factored with the presence or absence of resident predators (sea basses and moray eels) plus interference competitors (territorial damselfishes). Over 60 days, predators and competitors greatly reduced recruit abundance regardless of habitat complexity, but did not affect adult abundance. In contrast, increased habitat complexity had a strong positive effect on adult abundance and a weak positive effect on recruit abundance. Differential responses of recruits and adults may be related to the differential effects of habitat complexity on their primary predators. Sedentary recruits are likely most preyed upon by small resident predators that ambush prey, while larger adult fishes that forage widely and use reefs primarily for shelter are likely most preyed upon by large transient predators that chase prey. Increased habitat complexity may have inhibited foraging by transient predators but not resident predators. Results demonstrate the importance of habitat complexity to community dynamics, which is of concern given the accelerated degradation of habitats worldwide.

Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic reefs.

PubMed

Kikuchi, Ruy K P; Leão, Zelinda M A N; Oliveira, Marília D M

2010-05-01

Coral reefs along the Eastern Brazilian coast extend for a distance of 800 km from 12 degrees to 18 degrees S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90's in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA) protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA) Regional Node of the Global Coral Reef Monitoring Network (GCRMN) by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts) and similarity percentages (SIMPER) tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonics > 20cm per reef site) and of the coral recruits (colonies < 2cm per square meter), and the percentage of macroalgae indicate that the nearshore reefs, which are located less than 5 km from the coast, are in poorer condition than the reefs located more than 5 km off the coast. A higher density of coral colonies, lower macroalgal index, higher relative percent of turf algae and higher density of coral recruits in offshore reefs compared to the nearshore reefs are the conditions that contribute more than 80% to the dissimilarity between them. The offshore reefs are in better vital condition than the nearshore reefs and have a set of vitality indices more closely related to the Northwestern Atlantic reefs than the nearshore reef. These have been most severely impacted by the effects of direct human activities such as cuthrophic waters associated with sewage pollution, higher sedimentation rates and water turbidity, inadequate use of the reefs and over exploitation of their resources. The implementation of a more effective coral reef monitoring program in Bahia is mandatory, in order to improve the strategies for protection and management efforts of the reefs.

Detecting ecological change on coral reefs

NASA Astrophysics Data System (ADS)

Dustan, P.

2011-12-01

Remote sensing offers the potential to observe the response of coral reef ecosystems to environmental perturbations on a geographical scale not previously accessible. However, coral reef environments are optically, spatially, and temporally complex habitats which all present significant challenges for extracting meaningful information. Virtually every member of the reef community possesses some degree of photosynthetic capability. The community thus generates a matrix of fine scale features with bio-optical signatures that blend as the scale of observation increases. Furthermore, to have any validity, the remotely sensed signal must be "calibrated" to the bio-optics of the reef, a difficult and resource intensive process due to a convergence of photosynthetic light harvesting by green, red, and brown algal pigment systems. To make matters more complex, reefs are overlain by a seawater skin with its own set of hydrological optical challenges. Rather than concentrating on classification, my research has attempted to track change by following the variation in geo-referenced pixel brightness over time with a technique termed temporal texture. Environmental periodicities impart a phenology to the variation in brightness and departures from the norm are easily detected as statistical outliers. This opens the door to using current orbiting technology to efficiently examine large areas of sea for change. If hot spots are detected, higher resolution sensors and field studies can be focused as resources permit. While this technique does not identify the type of change, it is sensitive, simple to compute, easy to automate and grounded in ecological niche theory

Plastic waste associated with disease on coral reefs.

PubMed

Lamb, Joleah B; Willis, Bette L; Fiorenza, Evan A; Couch, Courtney S; Howard, Robert; Rader, Douglas N; True, James D; Kelly, Lisa A; Ahmad, Awaludinnoer; Jompa, Jamaluddin; Harvell, C Drew

2018-01-26

Plastic waste can promote microbial colonization by pathogens implicated in outbreaks of disease in the ocean. We assessed the influence of plastic waste on disease risk in 124,000 reef-building corals from 159 reefs in the Asia-Pacific region. The likelihood of disease increases from 4% to 89% when corals are in contact with plastic. Structurally complex corals are eight times more likely to be affected by plastic, suggesting that microhabitats for reef-associated organisms and valuable fisheries will be disproportionately affected. Plastic levels on coral reefs correspond to estimates of terrestrial mismanaged plastic waste entering the ocean. We estimate that 11.1 billion plastic items are entangled on coral reefs across the Asia-Pacific and project this number to increase 40% by 2025. Plastic waste management is critical for reducing diseases that threaten ecosystem health and human livelihoods. Copyright © 2018, The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease

PubMed Central

Williams, Gareth J.; Price, Nichole N.; Ushijima, Blake; Aeby, Greta S.; Callahan, Sean; Davy, Simon K.; Gove, Jamison M.; Johnson, Maggie D.; Knapp, Ingrid S.; Shore-Maggio, Amanda; Smith, Jennifer E.; Videau, Patrick; Work, Thierry M.

2014-01-01

Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylum Ustilaginomycetes and show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change. PMID:24452029

Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease.

PubMed

Williams, Gareth J; Price, Nichole N; Ushijima, Blake; Aeby, Greta S; Callahan, Sean; Davy, Simon K; Gove, Jamison M; Johnson, Maggie D; Knapp, Ingrid S; Shore-Maggio, Amanda; Smith, Jennifer E; Videau, Patrick; Work, Thierry M

2014-03-07

Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylum Ustilaginomycetes and show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change.

Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease

USGS Publications Warehouse

Williams, Gareth J.; Price, Nichole N.; Ushijima, Blake; Aeby, Greta S.; Callahan, Sean M.; Davy, Simon K.; Gove, Jamison M.; Johnson, Maggie D.; Knapp, Ingrid S.; Shore-Maggio, Amanda; Smith, Jennifer E.; Videau, Patrick; Work, Thierry M.

2014-01-01

Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylum Ustilaginomycetes and show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change.

Opposing Seasonal Trends in Seawater pH and Aragonite Saturation State on the Bermuda Coral Reef Platform Reveal Complex Controls on Seawater Chemistry by Biological and Physical Processes

NASA Astrophysics Data System (ADS)

Andersson, A. J.; Bates, N. R.; dePutron, S.; Collins, A.; Neely, K.; Best, M.; Noyes, T.

2011-12-01

To accurately predict future consequences of ocean acidification on coastal environments and ecosystems, it is critical to understand present conditions and variability. As part of the Bermuda ocean acidification and coral reef investigation (BEACON), significant efforts have been dedicated to characterize the complete surface seawater carbonic-acid system at different temporal and spatial scales on the Bermuda coral reef platform to understand current levels and variability in seawater CO2 parameters, reef metabolism, and future potential changes arising from ocean acidification. A four years monthly time-series of seawater carbonic-acid parameters at eight different locations on the Bermuda coral reef platform reveals strong seasonal patterns in dissolved inorganic carbon (DIC), total alkalinity (TA), pH, pCO2, and [HCO3-], and somewhat weaker trends in [CO32-] and saturation state with respect to CaCO3 minerals. Strong spatial gradients are also observed in DIC and TA during summertime owing to reef metabolism, but no or weak spatial gradients of these parameters are observed in the wintertime. Interestingly, maximum pH-sws (~8.15) is observed during wintertime when minimum aragonite saturation state (<3.0) is observed. In contrast, minimum pH-sws (~7.95) is observed in the summertime when maximum aragonite saturation state (>3.70) is observed. The observed trends and gradients point to complex relationships and interactions between seawater chemistry, biology and physics that need to be considered in the context of ocean acidification and in making future predictions on the effects of this perturbation on coral reefs and coastal ecosystems.

Field-trip guide to Columbia River flood basalts, associated rhyolites, and diverse post-plume volcanism in eastern Oregon

USGS Publications Warehouse

Ferns, Mark L.; Streck, Martin J.; McClaughry, Jason D.

2017-08-09

The Miocene Columbia River Basalt Group (CRBG) is the youngest and best preserved continental flood basalt province on Earth, linked in space and time with a compositionally diverse succession of volcanic rocks that partially record the apparent emergence and passage of the Yellowstone plume head through eastern Oregon during the late Cenozoic. This compositionally diverse suite of volcanic rocks are considered part of the La Grande-Owyhee eruptive axis (LOEA), an approximately 300-kilometer-long (185 mile), north-northwest-trending, middle Miocene to Pliocene volcanic belt located along the eastern margin of the Columbia River flood basalt province. Volcanic rocks erupted from and preserved within the LOEA form an important regional stratigraphic link between the (1) flood basalt-dominated Columbia Plateau on the north, (2) bimodal basalt-rhyolite vent complexes of the Owyhee Plateau on the south, (3) bimodal basalt-rhyolite and time-transgressive rhyolitic volcanic fields of the Snake River Plain-Yellowstone Plateau, and (4) the High Lava Plains of central Oregon.This field-trip guide describes a 4-day geologic excursion that will explore the stratigraphic and geochemical relationships among mafic rocks of the Columbia River Basalt Group and coeval and compositionally diverse volcanic rocks associated with the early “Yellowstone track” and High Lava Plains in eastern Oregon. Beginning in Portland, the Day 1 log traverses the Columbia River gorge eastward to Baker City, focusing on prominent outcrops that reveal a distal succession of laterally extensive, large-volume tholeiitic flood lavas of the Grande Ronde, Wanapum, and Saddle Mountains Basalt formations of the CRBG. These “great flows” are typical of the well-studied flood basalt-dominated Columbia Plateau, where interbedded silicic and calc-alkaline lavas are conspicuously absent. The latter part of Day 1 will highlight exposures of middle to late Miocene silicic ash-flow tuffs, rhyolite domes, and calc-alkaline lava flows overlying the CRBG across the northern and central parts of the LOEA. The Day 2 field route migrates to southern parts of the LOEA, where rocks of the CRBG are associated in space and time with lesser known and more complex silicic volcanic stratigraphy associated with middle Miocene, large-volume, bimodal basalt-rhyolite vent complexes. Key stops will provide a broad overview of the structure and stratigraphy of the middle Miocene Mahogany Mountain caldera and middle to late Miocene calc-alkaline lavas of the Owyhee basalt. Stops on Day 3 will progress westward from the eastern margin of the LOEA, examining a transition linking the Columbia River Basalt-Yellowstone province with a northwestward-younging magmatic trend of silicic volcanism that underlies the High Lava Plains of eastern Oregon. Initial field stops on Day 3 will examine key outcrops demonstrating the intercalated nature of middle Miocene tholeiitic CRBG flood basalts, prominent ash-flow tuffs, and “Snake River-type” large-volume rhyolite lava flows exposed along the Malheur River. Subsequent stops on Day 3 will focus upon the volcanic stratigraphy northeast of the town of Burns, which includes regional middle to late Miocene ash-flow tuffs, and lava flows assigned to the Strawberry Volcanics. The return route to Portland on Day 4 traverses across the western axis of the Blue Mountains, highlighting exposures of the widespread, middle Miocene Dinner Creek Tuff and aspects of Picture Gorge Basalt flows and northwest-trending feeder dikes situated in the central part of the CRBG province.

Did Oligocene crustal thickening precede basin development in northern Thailand? A geochronological reassessment of Doi Inthanon and Doi Suthep

NASA Astrophysics Data System (ADS)

Gardiner, Nicholas J.; Roberts, Nick M. W.; Morley, Christopher K.; Searle, Michael P.; Whitehouse, Martin J.

2016-01-01

The Doi Inthanon and Doi Suthep metamorphic core complexes in northern Thailand are comprised of amphibolite-grade migmatitic gneisses mantled by lower-grade mylonites and metasedimentary sequences, thought to represent Cordilleran-style core complexes exhumed through the mobilization of a low-angle detachment fault. Previous studies have interpreted two metamorphic events (Late Triassic and Late Cretaceous), followed by ductile extension between the late Eocene and late Oligocene, a model which infers movement on the detachment at ca. 40 Ma, and which culminates in a rapid unroofing of the complexes in the early Miocene. The Chiang Mai Basin, the largest such Cenozoic Basin in the region, lies immediately to the east. Its development is related to the extension observed at Doi Inthanon and Doi Suthep, however it is not definitively dated, and models for its development have difficulty reconciling Miocene cooling ages with Eocene detachment movement. Here we present new in-situ LA-ICP-MS and SIMS U-Pb age data of zircon and monazite grains from gneiss and leucogranite samples taken from Doi Inthanon and Doi Suthep. Our new zircon data exhibit an older age range of 221-210 Ma, with younger ages of ca. 72 Ma, and 32-26 Ma. Our monazite data imply an older age cluster at 83-67 Ma, and a younger age cluster of 34-24 Ma. While our data support the view of Indosinian basement being reworked in the Cretaceous, they also indicate a late Eocene-Oligocene tectonothermal event, resulting in prograde metamorphism and anatexis. We suggest that this later event is related to localized transpressional thickening associated with sinistral movement on the Mae Ping Fault, coupled with thickening at the restraining bend of the Mae Yuan Fault to the immediate west of Doi Inthanon. Further, this upper Oligocene age limit from our zircon and monazite data would imply a younger Miocene constraint on movement of the detachment, which, when combined with the previously recorded Miocene cooling ages, has implications for a model for the onset of extension and subsequent development of the Chiang Mai Basin in the early mid-Miocene.

Meteorologic, oceanographic, and geomorphic controls on circulation and residence time in a coral reef-lined embayment: Faga'alu Bay, American Samoa

NASA Astrophysics Data System (ADS)

Storlazzi, C. D.; Cheriton, O. M.; Messina, A. M.; Biggs, T. W.

2018-06-01

Water circulation over coral reefs can determine the degree to which reef organisms are exposed to the overlying waters, so understanding circulation is necessary to interpret spatial patterns in coral health. Because coral reefs often have high geomorphic complexity, circulation patterns and the duration of exposure, or "local residence time" of a water parcel, can vary substantially over small distances. Different meteorologic and oceanographic forcings can further alter residence time patterns over reefs. Here, spatially dense Lagrangian surface current drifters and Eulerian current meters were used to characterize circulation patterns and resulting residence times over different regions of the reefs in Faga'alu Bay, American Samoa, during three distinct forcing periods: calm, strong winds, and large waves. Residence times varied among different geomorphic zones of the reef and were reflected in the spatially varying health of the corals across the embayment. The relatively healthy, seaward fringing reef consistently had the shortest residence times, as it was continually flushed by wave breaking at the reef crest, whereas the degraded, sheltered, leeward fringing reef consistently had the longest residence times, suggesting this area is more exposed to land-based sources of pollution. Strong wind forcing resulted in the longest residence times by pinning the water in the bay, whereas large wave forcing flushed the bay and resulted in the shortest residence times. The effect of these different forcings on residence times was fairly consistent across all reef geomorphic zones, with the shift from wind to wave forcing shortening mean residence times by approximately 50%. Although ecologically significant to the coral organisms in the nearshore reef zones, these shortened residence times were still 2-3 times longer than those associated with the seaward fringing reef across all forcing conditions, demonstrating how the geomorphology of a reef environment sets a first-order control on reef health.

Feedbacks Between Wave Energy And Declining Coral Reef Structure: Implications For Coastal Morphodynamics

NASA Astrophysics Data System (ADS)

Grady, A. E.; Jenkins, C. J.; Moore, L. J.; Potts, D. C.; Burgess, P. M.; Storlazzi, C. D.; Elias, E.; Reidenbach, M. A.

2013-12-01

The incident wave energy dissipated by the structural complexity and bottom roughness of coral reef ecosystems, and the carbonate sediment produced by framework-building corals, provide natural shoreline protection and nourishment, respectively. Globally, coral reef ecosystems are in decline as a result of ocean warming and acidification, which is exacerbated by chronic regional stressors such as pollution and disease. As a consequence of declining reef health, many reef ecosystems are experiencing reduced coral cover and shifts to dominance by macroalgae, resulting in a loss of rugosity and thus hydrodynamic roughness. As coral reef architecture is compromised and carbonate skeletons are eroded, wave energy dissipation and sediment transport patterns--along with the carbonate sediment budget of the coastal environment--may be altered. Using a Delft3D numerical model of the south-central Molokai, Hawaii, fringing reef, we simulate the effects of changing reef states on wave energy and sediment transport. To determine the temporally-varying effects of biotic and abiotic stressors such as storms and bleaching on the reef structure and carbonate production, we couple Delft3D with CarboLOT, a model that simulates growth and competition of carbonate-producing organisms. CarboLOT is driven by the Lotka-Volterra population ecology equations and niche suitability principles, and accesses the CarboKB database for region-specific, carbonate-producing species information on growth rates, reproduction patterns, habitat suitability, as well as organism geometries. Simulations assess how changing reef states--which alter carbonate sediment production and reef morphology and thus hydrodynamic roughness--impact wave attenuation and sediment transport gradients along reef-fronted beaches. Initial results suggest that along fringing reefs having characteristics similar to the Molokai fringing reef, projected sea level rise will likely outpace coral reef accretion, and the increased residual wave energy transported to the coast may result in the alteration of alongshore sediment transport gradients and substantial changes to coastal morphology.

The influence of micro-topography and external bioerosion on coral-reef-building organisms: recruitment, community composition and carbonate production over time

NASA Astrophysics Data System (ADS)

Mallela, Jennie

2018-03-01

The continued health and function of tropical coral reefs is highly dependent on the ability of reef-building organisms to build large, complex, three-dimensional structures that continue to accrete and evolve over time. The recent deterioration of reef health globally, including loss of coral cover, has resulted in significant declines in architectural complexity at a large, reef-scape scale. Interestingly, the fine-scale role of micro-structure in initiating and facilitating future reef development and calcium carbonate production has largely been overlooked. In this study, experimental substrates with and without micro-ridges were deployed in the lagoon at One Tree Island for 34 months. This study assessed how the presence or absence of micro-ridges promoted recruitment by key reef-building sclerobionts (corals and encrusters) and their subsequent development at micro (mm) and macro (cm) scales. Experimental plates were examined after 11 and 34 months to assess whether long-term successional and calcification processes on different micro-topographies led to convergent or divergent communities over time. Sclerobionts were most prevalent in micro-grooves when they were available. Interestingly, in shallow lagoon reef sites characterised by shoals of small parrotfish and low urchin abundance, flat substrates were also successfully recruited to. Mean rates of carbonate production were 374 ± 154 (SD) g CaCO3 m-2 yr-1 within the lagoon. Substrates with micro-ridges were characterised by significantly greater rates of carbonate production than smooth substrates. The orientation of the substrate and period of immersion also significantly impacted rates of carbonate production, with CaCO3 on cryptic tiles increasing by 28% between 11 and 34 months. In contrast, rates on exposed tiles declined by 35% over the same time. In conclusion, even at sites characterised by small-sized parrotfish and low urchin density, micro-topography is an important settlement niche clearly favouring sclerobiont early life-history processes and subsequent carbonate production.

Subsurface Permian reef complexes of southern Tunisia: Shelf carbonate setting and paleogeographic implications

NASA Astrophysics Data System (ADS)

Zaafouri, Adel; Haddad, Sofiene; Mannaî-Tayech, Beya

2017-05-01

2-D seismic reflection sections, borehole data as well as published and unpublished data have been investigated to reconstruct the paleogeography of southern Tunisia during Middle to Late Permian times. Paleogeographical reconstruction based on the integration of petroleum well data and 2-D seismic facies interpretation shows three main depositional areas with very contrasting sedimentary pile. These are 1) a subsiding basin; 2) an outer shelf carbonate, and 3) an inner shelf carbonate. Based on typical electric responses of reef buildups to seismic wave, we shall urge that during Middle Permian times, the outer carbonate shelf was subject of reef barrier development. Lithology evidences from core samples show that reef framework correspond mainly to fossiliferous limestone and dolomite. The WNW-ESE recognized reef barrier led between latitudes 33° 10‧ 00″N and 33° 20‧ 00″N. The Tebaga of Medenine outcrop constitutes the northern-edge of this barrier. Westward it may be extended to Bir Soltane area whereas its extension eastward is still to be determined. Biogenic buildups took place preferentially over faulted Carboniferous and lower Paleozoic paleohighs resulting likely from the Hercynian orogeny. The subsiding basin is located north of Tebaga of Medenine outcrop where Upper Permian sedimentary sequence is made entirely of 4000 m deep marine green silty shale facies. These are ascribed to unorganized and chaotic reflectors. Inner carbonate shelf facies succession corresponds to a typical interbedding of shallow marine carbonate deposits, shale, dolomite, and anhydrite inducing parallel-layered of strong amplitude and good continuity reflectors. Also within the inner carbonate shelf patch reef or reef pinnacles have been identified based on their seismic signature particularly their low vertical development as compared to reef complexes. Southward, towards Sidi Toui area, the Upper Permian depositional sequence thins out and bears witness of land influences as entailed by the increase of silicoclastic sedimentary supply and the lack of marine fossil.

How will coral reef fish communities respond to climate-driven disturbances? Insight from landscape-scale perturbations.

PubMed

Adam, Thomas C; Brooks, Andrew J; Holbrook, Sally J; Schmitt, Russell J; Washburn, Libe; Bernardi, Giacomo

2014-09-01

Global climate change is rapidly altering disturbance regimes in many ecosystems including coral reefs, yet the long-term impacts of these changes on ecosystem structure and function are difficult to predict. A major ecosystem service provided by coral reefs is the provisioning of physical habitat for other organisms, and consequently, many of the effects of climate change on coral reefs will be mediated by their impacts on habitat structure. Therefore, there is an urgent need to understand the independent and combined effects of coral mortality and loss of physical habitat on reef-associated biota. Here, we use a unique series of events affecting the coral reefs around the Pacific island of Moorea, French Polynesia to differentiate between the impacts of coral mortality and the degradation of physical habitat on the structure of reef fish communities. We found that, by removing large amounts of physical habitat, a tropical cyclone had larger impacts on reef fish communities than an outbreak of coral-eating sea stars that caused widespread coral mortality but left the physical structure intact. In addition, the impacts of declining structural complexity on reef fish assemblages accelerated as structure became increasingly rare. Structure provided by dead coral colonies can take up to decades to erode following coral mortality, and, consequently, our results suggest that predictions based on short-term studies are likely to grossly underestimate the long-term impacts of coral decline on reef fish communities.

Conservation genetics and the resilience of reef-building corals.

PubMed

van Oppen, Madeleine J H; Gates, Ruth D

2006-11-01

Coral reefs have suffered long-term decline due to a range of anthropogenic disturbances and are now also under threat from climate change. For appropriate management of these vulnerable and valuable ecosystems it is important to understand the factors and processes that determine their resilience and that of the organisms inhabiting them, as well as those that have led to existing patterns of coral reef biodiversity. The scleractinian (stony) corals deposit the structural framework that supports and promotes the maintenance of biological diversity and complexity of coral reefs, and as such, are major components of these ecosystems. The success of reef-building corals is related to their obligate symbiotic association with dinoflagellates of the genus Symbiodinium. These one-celled algal symbionts (zooxanthellae) live in the endodermal tissues of their coral host, provide most of the host's energy budget and promote rapid calcification. Furthermore, zooxanthellae are the main primary producers on coral reefs due to the oligotrophic nature of the surrounding waters. In this review paper, we summarize and critically evaluate studies that have employed genetics and/or molecular biology in examining questions relating to the evolution and ecology of reef-building corals and their algal endosymbionts, and that bear relevance to coral reef conservation. We discuss how these studies can focus future efforts, and examine how these approaches enhance our understanding of the resilience of reef-building corals.

Characterization of heterogeneities from core X-ray scans and borehole wall images in a reefal carbonate reservoir: influence on the porosity structure.

NASA Astrophysics Data System (ADS)

Hebert, V.; Garing, C.; Pezard, P. A.; Gouze, P.; Maria-Sube, Y.; Camoin, G.; Lapointe, P.

2009-04-01

Petrophysical properties of rocks can be largely influenced by heterogeneities. This is particularly true in reefal carbonates, with heterogeneities due to the primary structure of the reef, the degradation of that structure into a fossil form, and fluid circulations with associated dissolutions and recrystallization. We report here a study conducted on Miocene reefal carbonates drilled in the context of salt water intrusion in coastal reservoirs. Salt water intrusion along coastlines is highly influenced by geological and petrophysical structures. In particular, heterogeneities and anisotropy in porous media (karsts, vugs…) control fluid flow and dispersion. A new experimental site has been developed in the South East of Mallorca Island (Spain) in the context of the ALIANCE EC project (2002-2005). This project aimed at developing a strategy for the quantitative analysis and description of fluid flow and salt transport in coastal carbonate aquifers. The site drilled the Miocene carbonate reef platform at Ses Sitjoles, 6 km inland, near the city of Campos. Sea water is found there at 60 to 80 m depth. The geological structure present multi-scale heterogeneities, often bound to either lateral variations of geological facies, or dissolution patterns. The Campos site provides a unique laboratory to study the heterogeneities of carbonate rocks with a saltwater intrusion and develop new borehole investigation methods in this context. The present study focuses on borehole geophysical measurements and images, and core scans. New image analysis methods have been developed to better characterize the presence of heterogeneities in terms of grain-size distribution, formation factor changes and porosity. Cores scans from RX tomography can lead to the extraction of petrophysical parameters from 3D images. For this, the AVIZO software was used here to represent the micro-porosity and vuggy porosity structure. Beyond core analyses, the optical and acoustic borehole wall images provide a direct look at meso-scale porosity beyond cm-scale heterogeneities, such as karstic channels and megapores. The reefal complex is dominated by moldic secondary porosity, which in the upper part of the boreholes. These heterogeneities are characterized by large and elongated molds mainly detected by the acoustic images. In slope, corresponding to the lower part of the structure, moldic porosity is characterized by small and round shaped molds. Vuggy porosity varies mainly from 5 to 40% along 100 m deep boreholes. But, in the slope part, the porosity is about 0% although it can reach 90% in karstic area. In all, the distribution of pore types is strongly controlled by that of lithofacies and water paleo-levels, leading to extensive cementation processes with the resulting occlusion of pore spaces. The combined analysis of porosity with complementary methods in terms of spacial resolution leads to the quantitative determination and description of microstructural heterogeneities in carbonate porous media. It is a key to model the reservoir mesoscale structure and fluid flows within it.

Freshwater Detention by Oyster Reefs: Quantifying a Keystone Ecosystem Service

PubMed Central

Olabarrieta, Maitane; Frederick, Peter; Valle-Levinson, Arnoldo

2016-01-01

Oyster reefs provide myriad ecosystem services, including water quality improvement, fisheries and other faunal support, shoreline protection from erosion and storm surge, and economic productivity. However, their role in directing flow during non-storm conditions has been largely neglected. In regions where oyster reefs form near the mouth of estuarine rivers, they likely alter ocean-estuary exchange by acting as fresh water “dams”. We hypothesize that these reefs have the potential to detain fresh water and influence salinity over extensive areas, thus providing a “keystone” ecosystem service by supporting estuarine functions that rely on the maintenance of estuarine (i.e., brackish) conditions in the near-shore environment. In this work, we investigated the effects of shore-parallel reefs on estuarine salinity using field data and hydrodynamic modeling in a degraded reef complex in the northeastern Gulf of Mexico. Results suggested that freshwater detention by long linear chains of oyster reefs plays an important role in modulating salinities, not only in the oysters’ local environment, but over extensive estuarine areas (tens of square kilometers). Field data confirmed the presence of salinity differences between landward and seaward sides of the reef, with long-term mean salinity differences of >30% between sides. Modeled results expanded experimental findings by illustrating how oyster reefs affect the lateral and offshore extent of freshwater influence. In general, the effects of simulated reefs were most pronounced when they were highest in elevation, without gaps, and when riverine discharge was low. Taken together, these results describe a poorly documented ecosystem service provided by oyster reefs; provide an estimate of the magnitude and spatial extent of this service; and offer quantitative information to help guide future oyster reef restoration. PMID:27936184

Early Pleistocene origin of reefs around Lanai, Hawaii

USGS Publications Warehouse

Webster, Jody M.; Clague, David A.; Faichney, Iain D.E.; Fullagar, Paul D.; Hein, James R.; Moore, James G.; Paull, Charles K.

2010-01-01

A sequence of submerged terraces (L1–L12) offshore Lanai was previously interpreted as reefal, and correlated with a similar series of reef terraces offshore Hawaii island, whose ages are known to be <500 ka. We present bathymetric, observational, lithologic and 51 87Sr/86Sr isotopic measurements for the submerged Lanai terraces ranging from −300 to −1000 m (L3–L12) that indicate that these terraces are drowned reef systems that grew in shallow coral reef to intermediate and deeper fore-reef slope settings since the early Pleistocene. Age estimates based on 87Sr/86Sr isotopic measurements on corals, coralline algae, echinoids, and bulk sediments, although lacking the precision (∼±0.23 Ma) to distinguish the age–depth relationship and drowning times of individual reefs, indicate that the L12–L3 reefs range in age from ∼1.3–0.5 Ma and are therefore about 0.5–0.8 Ma older than the corresponding reefs around the flanks of Hawaii. These new age data, despite their lack of precision and the influence of later-stage submarine diagenesis on some analyzed corals, clearly revise the previous correlations between the reefs off Lanai and Hawaii. Soon after the end of major shield building (∼1.3–1.2 Ma), the Lanai reefs initiated growth and went through a period of rapid subsidence and reef drowning associated with glacial/interglacial cycles similar to that experienced by the Hawaii reefs. However, their early Pleistocene initiation means they experienced a longer, more complex growth history than their Hawaii counterparts.

Oyster Reefs Support Coastal Resilience by Altering Nearshore Salinity: An Observational and Modeling Study to Quantify a "Keystone" Ecosystem Service

NASA Astrophysics Data System (ADS)

Kaplan, D. A.; Olabarrieta, M.; Frederick, P.; Valle-Levinson, A.

2016-12-01

Oyster reefs provide myriad ecosystem services, including water quality improvement, fisheries and other faunal support, shoreline protection from erosion and storm surge, and economic productivity. However, their role in directing flow during non-storm conditions has been largely neglected. In regions where oyster reefs form near the mouth of estuarine rivers, they likely alter ocean-estuary exchange by acting as fresh water "dams". We hypothesize that these reefs have the potential to detain fresh water and influence salinity over extensive areas, thus providing a "keystone" ecosystem service by supporting estuarine functions that rely on the maintenance of estuarine (i.e., brackish) conditions in the near-shore environment. In this work, we investigated the effects of shore-parallel reefs on near-shore salinity using field data and hydrodynamic modeling in a degraded reef complex in Suwannee Sound (Florida, USA). Results suggested that freshwater detention by long linear chains of oyster reefs plays an important role in modulating salinities, not only in the oysters' local environment, but over extensive estuarine areas (tens of square kilometers). Field data confirmed the presence of salinity differences between landward and seaward sides of the reef, with long-term mean salinity differences of >30% between sides. Modeled results expanded experimental findings by illustrating how oyster reefs affect the lateral and offshore extent of freshwater influence. In general, the effects of simulated reefs were most pronounced when they were highest in elevation, without gaps, and when riverine discharge was low. Taken together, these results describe a poorly documented ecosystem service provided by oyster reefs; provide an estimate of the magnitude and spatial extent of this service; and offer quantitative information to help guide future oyster reef restoration.

Freshwater Detention by Oyster Reefs: Quantifying a Keystone Ecosystem Service.

PubMed

Kaplan, David A; Olabarrieta, Maitane; Frederick, Peter; Valle-Levinson, Arnoldo

2016-01-01

Oyster reefs provide myriad ecosystem services, including water quality improvement, fisheries and other faunal support, shoreline protection from erosion and storm surge, and economic productivity. However, their role in directing flow during non-storm conditions has been largely neglected. In regions where oyster reefs form near the mouth of estuarine rivers, they likely alter ocean-estuary exchange by acting as fresh water "dams". We hypothesize that these reefs have the potential to detain fresh water and influence salinity over extensive areas, thus providing a "keystone" ecosystem service by supporting estuarine functions that rely on the maintenance of estuarine (i.e., brackish) conditions in the near-shore environment. In this work, we investigated the effects of shore-parallel reefs on estuarine salinity using field data and hydrodynamic modeling in a degraded reef complex in the northeastern Gulf of Mexico. Results suggested that freshwater detention by long linear chains of oyster reefs plays an important role in modulating salinities, not only in the oysters' local environment, but over extensive estuarine areas (tens of square kilometers). Field data confirmed the presence of salinity differences between landward and seaward sides of the reef, with long-term mean salinity differences of >30% between sides. Modeled results expanded experimental findings by illustrating how oyster reefs affect the lateral and offshore extent of freshwater influence. In general, the effects of simulated reefs were most pronounced when they were highest in elevation, without gaps, and when riverine discharge was low. Taken together, these results describe a poorly documented ecosystem service provided by oyster reefs; provide an estimate of the magnitude and spatial extent of this service; and offer quantitative information to help guide future oyster reef restoration.

Fringing coral reef condition decline: assembling the puzzle of human impact associated to coastal development.

NASA Astrophysics Data System (ADS)

Garza-Perez, J. R.; Lopez-Patoni, A.; Naranjo-Garcia, M. J.

2014-12-01

Coral cover at Akumal fringing coral reef decreased 50% in a 13 yr. period, while the adjacent coastal zone increased its human-modified surface (associated to urban-tourist development) in 192%. In the same period, the number of local residents only increased 20% (1088 to1362) but the visitors did in 50% from ca. 200,000 to ca. 300,000. In this coastal zone, the phreatic acts as a storage of nutrients and pollutants from sources related to human activity, thus having a chronic run-off towards the reef, with acute episodes during the rainy season, specially during the anomalous rainy season of 2013. Using videotransects for monitoring the benthic reef components, changes were detected: from 2000 to 2013 the algae cover increased 166%, the reef condition and the reef structure indexes decreased in 50%, and coral diseases incidence increased 25% after a spike increment of 150% in 2010. The role of anthropogenic-stress indicators (population, modified land area, nutrients) was explored along reef condition indicators (reef structure and diversity indexes, topographic complexity, benthic cover and coral diseases incidence) via spatial analysis and multivariate statistics. Spatial patterns of the change in reef condition derived from high-resolution satellite imagery also provided insight for the stressors analysis and their relationships along the study period. Stress indicators (land-modified area and population) are correlated to decreases in coral cover and in reef structure. Direct stressors as sedimentation, nutrients and pollutants seem to be related to the decrease in overall reef condition, although time-series data is lacking; the contextual interpretation of their effects, paired with benthic condition characteristics suggest a strong relationship between these stressors and the decrease in the condition of the reef.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buddemeier, R.W.; Oberdorfer, J.A.

A wide variety of forces can produce head gradients that drive the flow and advective mixing of internal coral reef pore waters. Oscillatory gradients that produce mixing result from wave and tide action. Sustained gradients result from wave and tide-induced setup and ponding, from currents impinging on the reef structure, from groundwater heads, and from density differenced (temperature or salinity gradients). These gradients and the permeabilities and porosities of reef sediments are such that most macropore environments are dominated by advection rather than diffusion. The various driving forces must be analyzed to determine the individual and combined magnitudes of theirmore » effects on a specific reef pore-water system. Pore-water movement controls sediment diagenesis, the exchange of nutrients between sediments and benthos, and coastal/island groundwater resources. Because of the complexity of forcing functions, their interactions with specific local reef environments, experimental studies require careful incorporation of these considerations into their design and interpretation. 8 refs., 3 figs., 1 tab.« less

Extinction vulnerability of coral reef fishes.

PubMed

Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron Macneil, M; McClanahan, Tim R; Ohman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

2011-04-01

With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate. © 2011 Blackwell Publishing Ltd/CNRS.

Extinction vulnerability of coral reef fishes

PubMed Central

Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron MacNeil, M; McClanahan, Tim R; Öhman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

2011-01-01

With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate. PMID:21320260

Carbon dioxide addition to coral reef waters suppresses net community calcification.

PubMed

Albright, Rebecca; Takeshita, Yuichiro; Koweek, David A; Ninokawa, Aaron; Wolfe, Kennedy; Rivlin, Tanya; Nebuchina, Yana; Young, Jordan; Caldeira, Ken

2018-03-22

Coral reefs feed millions of people worldwide, provide coastal protection and generate billions of dollars annually in tourism revenue. The underlying architecture of a reef is a biogenic carbonate structure that accretes over many years of active biomineralization by calcifying organisms, including corals and algae. Ocean acidification poses a chronic threat to coral reefs by reducing the saturation state of the aragonite mineral of which coral skeletons are primarily composed, and lowering the concentration of carbonate ions required to maintain the carbonate reef. Reduced calcification, coupled with increased bioerosion and dissolution, may drive reefs into a state of net loss this century. Our ability to predict changes in ecosystem function and associated services ultimately hinges on our understanding of community- and ecosystem-scale responses. Past research has primarily focused on the responses of individual species rather than evaluating more complex, community-level responses. Here we use an in situ carbon dioxide enrichment experiment to quantify the net calcification response of a coral reef flat to acidification. We present an estimate of community-scale calcification sensitivity to ocean acidification that is, to our knowledge, the first to be based on a controlled experiment in the natural environment. This estimate provides evidence that near-future reductions in the aragonite saturation state will compromise the ecosystem function of coral reefs.

Carbon dioxide addition to coral reef waters suppresses net community calcification

NASA Astrophysics Data System (ADS)

Albright, Rebecca; Takeshita, Yuichiro; Koweek, David A.; Ninokawa, Aaron; Wolfe, Kennedy; Rivlin, Tanya; Nebuchina, Yana; Young, Jordan; Caldeira, Ken

2018-03-01

Coral reefs feed millions of people worldwide, provide coastal protection and generate billions of dollars annually in tourism revenue. The underlying architecture of a reef is a biogenic carbonate structure that accretes over many years of active biomineralization by calcifying organisms, including corals and algae. Ocean acidification poses a chronic threat to coral reefs by reducing the saturation state of the aragonite mineral of which coral skeletons are primarily composed, and lowering the concentration of carbonate ions required to maintain the carbonate reef. Reduced calcification, coupled with increased bioerosion and dissolution, may drive reefs into a state of net loss this century. Our ability to predict changes in ecosystem function and associated services ultimately hinges on our understanding of community- and ecosystem-scale responses. Past research has primarily focused on the responses of individual species rather than evaluating more complex, community-level responses. Here we use an in situ carbon dioxide enrichment experiment to quantify the net calcification response of a coral reef flat to acidification. We present an estimate of community-scale calcification sensitivity to ocean acidification that is, to our knowledge, the first to be based on a controlled experiment in the natural environment. This estimate provides evidence that near-future reductions in the aragonite saturation state will compromise the ecosystem function of coral reefs.

Temporal dynamic of reef benthic communities in two marine protected areas in the Caribbean

NASA Astrophysics Data System (ADS)

Perera-Valderrama, Susana; Hernández-Arana, Héctor; Ruiz-Zárate, Miguel-Ángel; Alcolado, Pedro M.; Caballero-Aragón, Hansel; González-Cano, Jaime; Vega-Zepeda, Alejandro; Victoria-Salazar, Isael; Cobián-Rojas, Dorka; González-Méndez, Juliett; Hernández-González, Zaimiuri; de la Guardia-Llansó, Elena

2017-10-01

This study assessed the coral reef condition of two marine protected areas in the Caribbean: Guanahacabibes National Park, Cuba, and Costa Occidental de Isla Mujeres-Punta Cancun-Punta Nizuc National Park, Mexico, in a two-year period. The analyzed indicators for corals were live coral cover, diameter and height of the colonies, ancient and recent mortalities and abundance of recruits, which were evaluated in quadrats of 1 m2. In addition, it was estimated the coverage by morphofunctional groups of macroalgae in 25 × 25 cm quadrats and the density of the Diadema antillarum urchin in 1 m2 quadrats. The results showed differences between countries at broad spatial scales (hundreds of kilometers). Reefs of both MPAs seem to be in different stages of changes, which have been associated with deterioration of Caribbean reefs, toward the dominance of more resistant, non-tridimensional coral species, causing a decrease of the reef complexity that may leads to the reefs to collapse. At scales of kilometers (within MPAs), a similar pattern was found in reefs of GNP-Cuba and different trends were observed in reefs of CNP-Mexico. The observed differences between CNP-Mexico sites appear to be associated with the current tourism use patterns.

Dating intrusion and cooling of Cenozoic granitoids in the Dinarides of Southern Serbia and discussion of the geodynamic setting of Paleocene-Miocene magmatism in the Balkan Peninsula

NASA Astrophysics Data System (ADS)

Senecio, Schefer; Cvetković, Vladica; Fügenschuh, Bernhard; Kounov, Alexandre; Ovtcharova, Maria; Schaltegger, Urs; Schmid, Stefan

2010-05-01

This paper presents the results of high precision single grain U-Pb dating and Hf isotope analyses of thermally annealed and chemically abraded zircons from the Kopaonik, Drenje, Željin, Golija and Polumir intrusions in the inner Dinarides of southern Serbia. In addition, new zircon and apatite fission-track data together with local structural observations, allow for constraining the subsequent exhumation history of these intrusions. Two age groups were determined for the granitoid intrusions: (i) Oligocene intrusive bodies (Kopaonik, Drenje, Željin) ranging in age from 31.7 to 30.6 Ma and (ii) Miocene Golija and Polumir intrusions which emplaced at 20.58-20.17 and 18.06-17.74 Ma, respectively. The apatite fission-track modelling combined with zircon central ages show rapid cooling from above 300 to ca. 80 °C between 16 and 10 Ma for granitoids of both age groups, followed by rather slow cooling to surface temperatures for the last 10 Ma. Fast Middle Miocene cooling between 16 and 10 Ma is caused by extensional exhumation of the plutons that are located in the footwall of core-complexes. This documents that Miocene magmatism and core-complex formation leading to formation of the Pannonian basin also affected a part of the mountainous areas of the internal Dinarides. The discussion of an extensive set of age data from the literature and the geodynamic setting of the Balkan Peninsula reveals that there is no direct connection of the Dinaridic Late Eocene to earliest Miocene magmatic belt with contemporaneous Periadriatic intrusions in the Alps and along the Mid-Hungarian fault zone as proposed in the literature. We insist on the fact that the subduction polarity in the Alps, including that within the Western Carpathians north of the Mid-Hungarian fault zone, is opposite to that of the Dinarides during the given time span. Instead, we propose that Late Eocene to Oligocene magmatism, which affects the Adria-derived lower plate units of the internal Dinarides, may be caused by delamination of the Adriatic mantle from the overlying crust, associated with intra-plate convergence that propagates outward into the external Dinarides during this time interval. Miocene magmatism, on the other hand, is associated with core-complex formation at the southern rim of the Pannonian basin probably associated with the W-directed subduction of the European lithosphere beneath the Carpathians, possibly interfering with ongoing Dinaridic-Hellenic back-arc extension.

As, Bi, Hg, S, Sb, Sn and Te geochemistry of the J-M Reef, Stillwater Complex, Montana: constraints on the origin of PGE-enriched sulfides in layered intrusions

USGS Publications Warehouse

Zientek, M.L.; Fries, T.L.; Vian, R.W.

1990-01-01

The J-M Reef is an interval of disseminated sulfides in the Lower Banded series of the Stillwater Complex that is enriched in the platinum group elements (PGE). Palladium and Pt occur in solid solution in base-metal sulfides and as discrete PGE minerals. PGE minerals include sulfides, tellurides, arsenides, antimonides, bismuthides, and alloys with Fe, Sn, Hg, and Au. Several subpopulations can be delineated based on whole-rock chemical analyses for As, Bi, Cu, Hg, Pd, Pt, S, Sb and Te for samples collected from and adjacent to the J-M Reef. In general, samples from within the reef have higher Pt/Cu, Pd/Cu, Pd/Pt, Te/Bi and S/(Te+Bi) than those collected adjacent to the reef. Vertical compositional profiles through the reef suggest that Pd/Cu and Pt/Cu decrease systematically upsection from mineralized to barren rock. The majority of samples with elevated As, Sb and Hg occur adjacent to the reef, not within it, or in sulfide-poor rocks. Neither magma mixing nor fluid migration models readily explain why the minor quantities of sulfide minerals immediately adjacent to the sulfide-enriched layers that form the J-M Reef have different element ratios than the sulfide minerals that form the reef. If all the sulfides formed by exsolution during a magma mixing event and the modal proportion of sulfide now in the rocks are simply the result of mechanical processes that concentrated the sulfides into some layers and not others, then the composition of the sulfide would not be expected to be different. Models that rely upon ascending liquids or fluids are incompatible with the presence of sulfides that are not enriched in PGE immediately below or interlayered with the PGE-enriched sulfides layers. PGE-enriched postcumulus fluids should have reacted to the same extent with sulfides immediately outside the reef as within the reef. One explanation is that some of the sulfide minerals in the rocks outside the reef have a different origin than those that make up the reef. The sulfide minerals that form the reef may represent a cumulus sulfide phase that formed as the result of a magma-mixing event, achieved its high PGE contents at that time, and accumulated to form a layer. The rocks outside the reef may contain a large proportion of postcumulus sulfide minerals that formed as the last dregs of intercumulus liquids trapped in the interstitial spaces between the cumulus grains reached sulfur saturation and exsolved a sulfide liquid or precipitated a sulfide mineral. The PGE contents of these sulfides would be expected to be less than the cumulus sulfides that form the reef since they would have equilibrated with a much smaller volume of silicate liquid. Another explanation is that some of the sulfide droplets that formed as a result of the mixing event were trapped as inclusions in silicate minerals soon after they formed. This would reduce the amount of magma these sulfide droplets could equilibrate with and effectively reduce their PGE tenor. ?? 1990.

Taphonomy of coral reefs from Southern Lagoon of Belize

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westphall, M.J.; Ginsburg, R.N.

1985-02-01

The Southern Lagoon of the Belize barrier complex, an area of some 600 km/sup 2/, contains a tremendous number of lagoon reefs, which range in size from patches several meters across to rhomboidal-shaped structures several kilometers in their long dimension. These lagoon reefs are remarkable because they have Holocene sediment accumulations in excess of 13 m consisting almost entirely of coral debris and lime mud and sand, and rise up to 30 m above the surrounding lagoon floor with steeply sloping sides (50-80/sup 0/), yet are totally uncemented. The reef-building biota and their corresponding deposits were studied at a representativemore » reef, the rhomboidal complex of Channel Cay. As with many of the reefs in this area, the steeply sloping flanks of Channel Cay are covered mainly by the branched staghorn coral Acropora cervicornis and ribbonlike and platy growth of Agaricia spp. The living corals are not cemented to the substrate, but are merely intergrown. Fragmented pieces of corals accumulate with an open framework below the living community; this open framework is subsequently infilled by lime muds and sands produced mainly from bioerosion. Results from probing and coring suggest that the bafflestone fabric of coral debris and sediment extends at least 13 m into the subsurface. Radiocarbon-age estimates indicate these impressive piles of coral rubble and sediment have accumulated in the past 9000 yr (giving a minimum accumulation rate of 1.4 m/1000 yr) and illustrate the potential for significant carbonate buildups without the need for early lithification.« less

The lateral boundary of a metamorphic core complex: the Moutsounas shear zone on Naxos, Cyclades, Greece

NASA Astrophysics Data System (ADS)

Cao, S.; Neubauer, F.

2012-04-01

One of the apparently best investigated metamorphic core complexes all over world is that of Naxos in the Aegean Sea and numerous high-quality data on structures and microfabrics have been published. Among these structures is the Naxos-Paros ductile low-angle fault (Gautier et al., 1993), which is located along the northern margin of Naxos and which is part of the North Cycladic Detachment System (Jolivet et al., 2010). There, structural evidence indicates that the hanging wall of the core complex experienced large-scale top-to-the-north (ca. 010°) transport along a low-angle detachment fault. Interestingly no attention has been paid on the well exposed boundary fault on the eastern margin of the Naxos Island, which is even not mentioned in the lierarure. We denote this fault as Moutsounas shear zone, which represents the lateral boundary of the Naxos metamorphic core complex. The Naxos metamorphic core complex is a N-trending elongated dome, which exposes on its eastern side moderately E-dipping micaschists and marbles, which are largely well annealed due to late heating. These annealed rocks grade towards the Moutsounas Peninsula in retrogressed sheared rocks, mostly phyllonitic micaschists and phyllites with an E-dipping foliation and a ca. NNE-trending subhorizontal stretching lineation. Shear bands, asymmetric fringes around rigid clasts and oblique mineralized extension veins consistently indicate top-to-the-NNE shear. The shear zone is structurally overlain by hydrothermally altered Miocene conglomerates, which contain no pebbles from the Naxos metamorphic core complex but exclusively from the ophiolitic hangingwall unit. Miocene rocks are exposed both on the northern and southern edge of the Moutsounas Peninsula. Their bedding is variable but dips generally towards NW, oblique to the detachment fault, which dips with a medium-angle towards east indicating therefore a rollover structure. The Miocene succession is overlain by subhorizontal conglomerates of Pliocene age, which form the main portion of the Moutsounas Peninsula and which contain numerous clasts, mainly marble, of the metamorphic core complex. These sedimentary data indicate that exhumation of the Naxos metamorphic core complex postdate deposition of Miocene successions and predate Pliocene rocks. We interpret the Moutsounas shear zone as a lateral boundary of the Naxos migmatite dome and relate their main activity with top NNE-shear with the main stage of updoming during migmatite formation and granite uplift between ca. 15 and 11 Ma.

Complex and interactive effects of ocean acidification and temperature on epilithic and endolithic coral-reef turf algal assemblages

NASA Astrophysics Data System (ADS)

Johnson, Maggie D.; Comeau, Steeve; Lantz, Coulson A.; Smith, Jennifer E.

2017-12-01

Turf algal assemblages are ubiquitous primary producers on coral reefs, but little is known about the response of this diverse group to ocean acidification (OA) across different temperatures. We tested the hypothesis that CO2 influences the functional response of epilithic and endolithic turf assemblages to increasing temperature. Replicate carbonate plugs covered by turf were collected from the reef and exposed to ambient and high pCO2 (1000 µatm) conditions for 3 weeks. Each pCO2 treatment was replicated across six temperatures (24.0-31.5 °C) that spanned the full seasonal temperature range on a fringing reef in Moorea, French Polynesia, and included one warming treatment (3 °C above daily average temperatures). Temperature and CO2 enrichment had complex, and sometimes interactive, effects on turf metabolism and growth. Photosynthetic and respiration rates were enhanced by increasing temperature, with an interactive effect of CO2 enrichment. Photosynthetic rates were amplified by high CO2 in the warmest temperatures, while the increase in respiration rates with temperature were enhanced under ambient CO2. Epilithic turf growth rates were not affected by temperature, but increased in response to CO2 enrichment. We found that CO2 and temperature interactively affected the endolithic assemblage, with the highest growth rates under CO2 enrichment, but only at the warmest temperatures. These results demonstrate how OA may influence algal physiology and growth across a range of ecologically relevant temperatures, and indicate that the effects of CO2 enrichment on coral-reef turf assemblages can be temperature dependent. The complex effects of CO2 enrichment and temperature across a suite of algal responses illustrates the importance of incorporating multiple stressors into global change experiments.

Multiscale approach reveals that Cloudina aggregates are detritus and not in situ reef constructions

NASA Astrophysics Data System (ADS)

Mehra, Akshay; Maloof, Adam

2018-03-01

The earliest metazoans capable of biomineralization appeared during the late Ediacaran Period (635–541 Ma) in strata associated with shallow water microbial reefs. It has been suggested that some Ediacaran microbial reefs were dominated (and possibly built) by an abundant and globally distributed tubular organism known as Cloudina. If true, this interpretation implies that metazoan framework reef building—a complex behavior that is responsible for some of the largest bioconstructions and most diverse environments in modern oceans—emerged much earlier than previously thought. Here, we present 3D reconstructions of Cloudina populations, produced using an automated serial grinding and imaging system coupled with a recently developed neural network image classifier. Our reconstructions show that Cloudina aggregates are composed of transported remains while detailed field observations demonstrate that the studied reef outcrops contain only detrital Cloudina buildups, suggesting that Cloudina played a minor role in Ediacaran reef systems. These techniques have wide applicability to problems that require 3D reconstructions where physical separation is impossible and a lack of density contrast precludes tomographic imaging techniques.

Multi-scale interactions between local hydrography, seabed topography, and community assembly on cold-water coral reefs

NASA Astrophysics Data System (ADS)

Henry, L.-A.; Moreno Navas, J.; Roberts, J. M.

2013-04-01

We investigated how interactions between hydrography, topography and species ecology influence the assembly of species and functional traits across multiple spatial scales of a cold-water coral reef seascape. In a novel approach for these ecosystems, we used a spatially resolved complex three-dimensional flow model of hydrography to help explain assembly patterns. Forward-selection of distance-based Moran's eigenvector mapping (dbMEM) variables identified two submodels of spatial scales at which communities change: broad-scale (across reef) and fine-scale (within reef). Variance partitioning identified bathymetric and hydrographic gradients important in creating broad-scale assembly of species and traits. In contrast, fine-scale assembly was related more to processes that created spatially autocorrelated patches of fauna, such as philopatric recruitment in sessile fauna, and social interactions and food supply in scavenging detritivores and mobile predators. Our study shows how habitat modification of reef connectivity and hydrography by bottom fishing and renewable energy installations could alter the structure and function of an entire cold-water coral reef seascape.

Depth and coral cover drive the distribution of a coral macroborer across two reef systems.

PubMed

Maher, Rebecca L; Johnston, Michelle A; Brandt, Marilyn E; Smith, Tyler B; Correa, Adrienne M S

2018-01-01

Bioerosion, the removal of calcium carbonate from coral frameworks by living organisms, influences a variety of reef features, from their topographic complexity to the net balance of carbonate budgets. Little is known, however, about how macroborers, which bore into reef substrates leaving traces greater than 0.1 mm diameter, are distributed across coral reefs, particularly reef systems with high (>50%) stony coral cover or at mesophotic depths (≥30 m). Here, we present an accurate and efficient method for quantifying macroborer densities from stony coral hosts via image analysis, using the bioeroding barnacle, Lithotrya dorsalis, and its host coral, Orbicella franksi, as a case study. We found that in 2014, L. dorsalis densities varied consistently with depth and host percent cover in two Atlantic reef systems: the Flower Garden Banks (FGB, northwest Gulf of Mexico) and the U.S. Virgin Islands (USVI). Although average barnacle density was nearly 4.5 times greater overall in the FGB than in the USVI, barnacle density decreased with depth in both reef regions. Barnacle density also scaled negatively with increasing coral cover in the study areas, suggesting that barnacle populations are not strictly space-limited in their distribution and settlement opportunities. Our findings suggest that depth and host coral cover, and potentially, local factors may strongly influence the abundance of macroborers, and thus the rate of CaCO3 loss, in a given reef system. Our image analysis method for quantifying macroborers can be standardized across historical and modern reef records to better understand how borers impact host growth and reef health.

Controls on the quality of Miocene reservoirs, southern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Gutiérrez Paredes, Hilda Clarisa; Catuneanu, Octavian; Hernández Romano, Ulises

2018-01-01

An investigation was conducted to determine the main controls on the reservoir quality of the middle and upper Miocene sandstones in the southern Gulf of Mexico based on core descriptions, thin section petrography and petrophysical data; as well as to explore the possible link between the sequence stratigraphic framework, depositional facies and diagenetic alterations. The Miocene deep marine sandstones are attributed to the falling-stage, lowstand, and transgressive systems tracts. The middle Miocene falling-stage systems tract includes medium-to very fine-grained, and structureless sandstones deposited in channels and frontal splays, and muddy sandstones, deposited in lobes of debrites. The lowstand and transgressive systems tracts consist of medium-to very fine-grained massive and normally graded sandstones deposited in channel systems within frontal splay complexes. The upper Miocene falling-stage systems tract includes medium-to coarse-grained, structureless sandstones deposited in channel systems and frontal splay, as well as lobes of debrites formed by grain flows and hybrid-flow deposits. The lowstand and transgressive systems tracts include fine-grained sandstones deposited in overbank deposits. The results reveal that the depositional elements with the best reservoir quality are the frontal splays deposited during the falling-stage system tracts. The reservoir quality of the Miocene sandstones was controlled by a combination of depositional facies, sand composition and diagenetic factors (mainly compaction and calcite cementation). Sandstone texture, controlled primarily by depositional facies appears more important than sandstone composition in determining reservoir quality; and compaction was more important than cementation in porosity destruction. Compaction was stopped, when complete calcite cementation occurred.

The importance of spatial fishing behavior for coral reef resilience

NASA Astrophysics Data System (ADS)

Rassweiler, A.; Lauer, M.; Holbrook, S. J.

2016-02-01

Coral reefs are dynamic systems in which disturbances periodically reduce coral cover but are normally followed by recovery of the coral community. However, human activity may have reduced this resilience to disturbance in many coral reef systems, as an increasing number of reefs have undergone persistent transitions from coral-dominated to macroalgal-dominated community states. Fishing on herbivores may be one cause of reduced reef resilience, as lower herbivory can make it easier for macroalgae to become established after a disturbance. Despite the acknowledged importance of fishing, relatively little attention has been paid to the potential for feedbacks between ecosystem state and fisher behavior. Here we couple methods from environmental anthropology and ecology to explore these feedbacks between small-scale fisheries and coral reefs in Moorea, French Polynesia. We document how aspects of ecological state such as the abundance of macroalgae affect people's preference for fishing in particular lagoon habitats. We then incorporate biases towards fishing in certain ecological states into a spatially explicit bio-economic model of ecological dynamics and fishing in Moorea's lagoons. We find that feedbacks between spatial fishing behavior and ecological state can have critical effects on coral reefs. Presence of these spatial behaviors consistently leads to more coherence across the reef-scape. However, whether this coherence manifests as increased resilience or increased fragility depends on the spatial scales of fisher movement and the magnitudes of disturbance. These results emphasize the potential importance of spatially-explicit fishing behavior for reef resilience, but also the complexity of the feedbacks involved.

Contrasting movements and connectivity of reef-associated sharks using acoustic telemetry: implications for management.

PubMed

Espinoza, Mario; Lédée, Elodie J I; Simpfendorfer, Colin A; Tobin, Andrew J; Heupel, Michelle R

2015-12-01

Understanding the efficacy of marine protected areas (MPAs) for wide-ranging predators is essential to designing effective management and conservation approaches. The use of acoustic monitoring and network analysis can improve our understanding of the spatial ecology and functional connectivity of reef-associated species, providing a useful approach for reef-based conservation planning. This study compared and contrasted the movement and connectivity of sharks with different degrees of reef association. We examined the residency, dispersal, degree of reef connectivity, and MPA use of grey reef (Carcharhinus amblyrhynchos), silvertip (C. albimarginatus), and bull (C. leucas) sharks monitored in the central Great Barrier Reef (GBR). An array of 56 acoustic receivers was used to monitor shark movements on 17 semi-isolated reefs. Carcharhinus amblyrhynchos and C. albimarginatus were detected most days at or near their tagging reef. However, while C. amblyrhynchos spent 80% of monitoring days in the array, C. albimarginatus was only detected 50% of the time. Despite both species moving similar distances (< 50 km), a large portion of the population of C. albimarginatus (71%) was detected on multiple reefs and moved more frequently between reefs and management zones than C. amblyrhynchos. Carcharhinus leucas was detected less than 20% of the time within the tagging array, and 42% of the population undertook long-range migrations to other arrays in the GBR. Networks derived for C. leucas were larger and more complex than those for C. amblyrhynchos and C. albimarginatus. Our findings suggest that protecting specific reefs based on prior knowledge (e.g., healthier reefs with high fish biomass) and increasing the level of protection to include nearby, closely spaced reef habitats (< 20 km) may perform better for species like C. albimarginatus than having either a single or a network of isolated MPAs. This design would also provide protection for larger male C. amblyrhynchos, which tend to disperse more and use larger areas than females. For wide-ranging sharks like C. leucas, a combination of spatial planning and other alternative measures is critical. Our findings demonstrate that acoustic monitoring can serve as a useful platform for designing more effective MPA networks for reef predators displaying a range of movement patterns.

Radar, an optimum remote-sensing tool for detailed plate tectonic analysis and its application to hydrocarbon exploration (an example in Irian Jaya Indonesia)

NASA Technical Reports Server (NTRS)

Froidevaux, C. M.

1980-01-01

Geometric, geomorphic, and structural information derived from the examination of radar imagery and combined with geologic and geophysical evidences strongly indicates that Salawati Island was attached to the Irian Jaya mainland during the time of Miocene lower Pliocene reef development, and that it was separated in middle Pliocene to Pleistocene time, opening the Sele Strait rift zone. The island moved 17.5 km southwestward after an initial counterclockwise rotation of 13 deg. The rift zone is subsequent to the creation of the large left lateral Sorong fault zone that is part of the transitional area separating the westward-moving Pacific plate from the relatively stable Australian plate. The motion was triggered during a widespread magmatic intrusion of the Sorong fault zone, when the basalt infiltrated a right lateral fault system in the area of the present Sele Strait.

Cruise report RV Ocean Surveyor Cruise 0-1-00-GM; the bathymetry and acoustic backscatter of the Pinnacles area; northern Gulf of Mexico, May 23, through June 10, 2000; Venice, LA to Venice, LA

USGS Publications Warehouse

Gardner, James V.; Sulak, Kenneth J.; Dartnell, Peter; Hellequin, Laurent; Calder, Brian R.; Mayer, Larry A.

2000-01-01

An extensive deep (~100 m) reef tract occurs on the Mississippi-Alabama outer continental shelf (OCS). The tract, known as "The Pinnacles", is apparently part of a sequence of drowned reef complexes along the "40-fathom" shelf edge of the northern Gulf of Mexico (Ludwick and Walton, 1957). It is critical to determine the accurate geomorphology of deep-reefs because of their importance as benthic habitats for fisheries. The Pinnacles were mapped by Ludwick and Walton (1957) using a single-beam echo sounder but the spatial extent and morphology were interpreted from a series of widely separated, poorly navigated bathymetric profiles. Other recent studies, supported by Minerals Management Service (MMS), used towed sidescan sonars and single-channel seismic-reflection profiling. None of the existing studies provide the quality of geomorphic data necessary for reasonable habitat studies. The fish faunas of shallow hermatypic reefs have been well studied, but those of deep ahermatypic reefs have relatively ignored. The ecology of deep ahermatypic reefs is fundamentally different from hermatipic reefs because autochthonous intracellular symbiotic zooxanthellae (the carbon source for hermatypic corals) do not form the base of the trophic web. Instead, exogenous plankton, transported to the reef by currents, serves as the primary carbon source. Deep OCS reefs also lie below the practical working depths for SCUBA; consequently, remote investigations from a ship or in situ investigations using submersibles or ROVs are required. Community structure and trophodynamics of demersal fishes of the Pinnacles are presently the focus of USGS reseach. A goal of the research is to answer questions concerning the relataive roles played by geomorphology and surficial geology in the interaction with and control of biological differentiation. OCS reefs are important because we now know that such areas are important coral reef fish havens, key spawning 2 sites, and a critical early larval and juvenile habitats for economically important sport/food fishes. Also, deep-reef ecosystems as well as the fish populations they sustain are impacted by intensive oil-field development. It is now known that deep OCS reefs function as a key source of re-population (via seasonal and ontogenetic migration) of already heavily impacted inshore reefs. A reflection of this realization is the recent closure by the Gulf States Fisheries Management Council of a 600 mi 2 area of the Florida Middle Grounds (another unmapped major "40-fathom" OCS reef complex) to commercial fishing to preserve grouper spawning aggregations. It is known that the Pinnacles reefs support a lush fauna of ahermatypic hard corals, soft corals, black corals, sessile crinoids and sponges—together forming a living habitat for a well-developed fish fauna. The fish fauna comprises typical Caribbean reef fishes and Carolinian shelf fishes, plus epipelagic fishes, and a few deep-sea fishes. The base of the megafaunal invertebrate food web is plankton, borne by essentially continuous semi-laminar currents flowing predominantly out of the SW, up, along and across the shelf edge. These currents are intercepted by pinnacles reefs, which lie roughly in two linear tracts, parallel to the coastline (see fig. 1 in report). USGS research initiated in 1997 (Sulak et al., in progress) has demonstrated that the Pinnacles reef fish fauna is dominated by planktivorous fishes. Ongoing food habits, trophic web and stable isotope analyses by the USGS are reinforcing a basic picture of deep OCS reefs as ecosystems based on exogenous current-borne plankton. Long-term current meter deployments have demonstrated that the >3 m,

"Species" radiations of symbiotic dinoflagellates in the Atlantic and Indo-Pacific since the Miocene-Pliocene transition.

PubMed

Lajeunesse, Todd C

2005-03-01

Endosymbiotic dinoflagellates, or "zooxanthellae," are required for the survival of a diverse community of invertebrates that construct and dominate shallow, tropical coral reef ecosystems. Molecular systematics applied to this once understudied symbiont partner, Symbiodinium spp., divide the group into divergent lineages or subgeneric "clades." Within each clade, numerous closely related "types," or species, exhibit distinctive host taxon, geographic, and/or environmental distributions. This diversity is greatest in clade C, which dominates the Indo-Pacific host fauna and shares dominance in the Atlantic-Caribbean with clade B. Two "living" ancestors in this group, C1 and C3, are common to both the Indo-Pacific and Atlantic-Caribbean. With these exceptions, each ocean possesses a diverse clade C assemblage that appears to have independently evolved (adaptively radiated) through host specialization and allopatric differentiation. This phylogeographic evidence suggests that a worldwide selective sweep of C1/C3, or their progenitor, must have occurred before both oceans separated. The probable timing of this event corresponds with the major climactic changes and low CO(2) levels of the late Miocene and/or early Pliocene. Subsequent bursts of diversification have proceeded in each ocean since this transition. An ecoevolutionary expansion to numerous and taxonomically diverse hosts by a select host-generalist symbiont followed by the onset of rapid diversification suggests a radical process through which coral-algal symbioses respond and persist through the vicissitudes of planetary climate change.

The brittle stage of the exhumation of a metamorphic core complex: Naxos, Cyclades, Greece and some general rules

NASA Astrophysics Data System (ADS)

Neubauer, F.; Cao, S.

2012-04-01

Structures of hangingwall units of major detachment systems in extensional settings leading to metamorphic core complexes are equally important to the generally well-studied footwall rocks. Here, we describe hanging-wall structures of the North-Cycladic Detachment System on Naxos Island of the Aegean Sea and found that they well monitor the structural evolution of hanging blocks complementary to the footwall structures, vertical fluid flow as well as late-stage inversion of the whole extensional system. On Naxos, Upper Oligocene-Miocene and Pliocene sedimentary successions are deposited on the hangingwall unit, which is largely an ophiolite. The Upper Oligocene-Miocene and Pliocene sedimentary successions are separated by a hiatus arguing for a two-step evolution. Whereas the first step, Miocene, indicate moderate subsidence and relief, and only denudation of the hangingwall unit, the Pliocene conglomerates indicate a sharply increasing relief and an over-steepened topography. Hydrothermal systems developed in hangingwall rock succession (e.g. Miocene at Steladia) play an important role and resulted in large-scale silica precipitation and associated alteration similar as these found in subvolcanic epithermal systems. This constrains a close link between footwall granodiorite intrusion and near-surface processes. The Pliocene coarse boulder conglomerate with its abundant first appearance of granite/granodiorite, and subsequent marble-rich debris on distant places like Palatia indicate a sudden erosion and high-gradient relief leading to erosion of the mantle of the migmatite dome during Pliocene. On Naxos, we recognize, therefore, a three-stage tectonic evolution in the hangingwall unit: (i) moderate subsidence of an Upper Oligocene-Miocene basin, in part below sea level; (2) a second stage with deposition of Pliocene coarse conglomerates, and (iii) post-Pliocene faulting affecting the conglomerates. During the second stage, surface exposure of the metamorphic core complex was reached resulting in catastrophic alluvial fans. Structural data from the Upper Oligocene-Miocene rocks indicate that NNE-SSW extension still prevailed up to the Miocene/Pliocene boundary. Together with structural data from Pliocene conglomerates, we can distinguish between three major events: The first stage is characterized by mostly NNE-dipping and subordinate SSW-dipping normal faults indicating together ca. NNE-SSW extension. A second palaeostress tensor group (B) mainly comprises ca. NW-trending dextral and WSW-trending sinistral strike-slip faults indicating together ca. E-W strike-slip compression and monitor, therefore, inversion and compression perpendicular to the previous extension direction. The third palaeostress tensor group (C) is characterized by dominating mostly NE-trending subvertical sinistral strike-slip faults and steep NNW-trending dextral strike-slip faults constituting together ca. N-S strike-slip compression. In a few cases, S- to SW-dipping reverse faults also occur. On a general level, our study allows for the following major conclusions: (1) Structures of hangingwall units of major detachments above metamorphic core complexes are equally important compared to the generally well-studied footwall rocks. They allow date several tectonic events not necessarily found in footwall rocks. (2) On Naxos, we can distinguish between three major tectonic events, which are in accordance with large-scale tectonic processes in the Aegean Sea: (a) ca. NNE-SSW extension; (b) ca. E-W strike-slip compression and monitor therefore inversion and compression perpendicular to the previous extension direction, and (c) N-S strike-slip compression.

Post-Disturbance Stability of Fish Assemblages Measured at Coarse Taxonomic Resolution Masks Change at Finer Scales.

PubMed

Ceccarelli, Daniela M; Emslie, Michael J; Richards, Zoe T

2016-01-01

Quantifying changes to coral reef fish assemblages in the wake of cyclonic disturbances is challenging due to spatial variability of damage inherent in such events. Often, fish abundance appears stable at one spatial scale (e.g. reef-wide), but exhibits substantial change at finer scales (e.g. site-specific decline or increase). Taxonomic resolution also plays a role; overall stability at coarse taxonomic levels (e.g. family) may mask species-level turnover. Here we document changes to reef fish communities after severe Tropical Cyclone Ita crossed Lizard Island, Great Barrier Reef. Coral and reef fish surveys were conducted concurrently before and after the cyclone at four levels of exposure to the prevailing weather. Coral cover declined across all exposures except sheltered sites, with the largest decline at exposed sites. There was no significant overall reduction in the total density, biomass and species richness of reef fishes between 2011 and 2015, but individual fish taxa (families and species) changed in complex and unpredictable ways. For example, more families increased in density and biomass than decreased following Cyclone Ita, particularly at exposed sites whilst more fish families declined at lagoon sites even though coral cover did not decline. All sites lost biomass of several damselfish species, and at most sites there was an increase in macroinvertivores and grazers. Overall, these results suggest that the degree of change measured at coarse taxonomic levels masked high species-level turnover, although other potential explanations include that there was no impact of the storm, fish assemblages were impacted but underwent rapid recovery or that there is a time lag before the full impacts become apparent. This study confirms that in high-complexity, high diversity ecosystems such as coral reefs, species level analyses are essential to adequately capture the consequences of disturbance events.

Post-Disturbance Stability of Fish Assemblages Measured at Coarse Taxonomic Resolution Masks Change at Finer Scales

PubMed Central

Ceccarelli, Daniela M.

2016-01-01

Quantifying changes to coral reef fish assemblages in the wake of cyclonic disturbances is challenging due to spatial variability of damage inherent in such events. Often, fish abundance appears stable at one spatial scale (e.g. reef-wide), but exhibits substantial change at finer scales (e.g. site-specific decline or increase). Taxonomic resolution also plays a role; overall stability at coarse taxonomic levels (e.g. family) may mask species-level turnover. Here we document changes to reef fish communities after severe Tropical Cyclone Ita crossed Lizard Island, Great Barrier Reef. Coral and reef fish surveys were conducted concurrently before and after the cyclone at four levels of exposure to the prevailing weather. Coral cover declined across all exposures except sheltered sites, with the largest decline at exposed sites. There was no significant overall reduction in the total density, biomass and species richness of reef fishes between 2011 and 2015, but individual fish taxa (families and species) changed in complex and unpredictable ways. For example, more families increased in density and biomass than decreased following Cyclone Ita, particularly at exposed sites whilst more fish families declined at lagoon sites even though coral cover did not decline. All sites lost biomass of several damselfish species, and at most sites there was an increase in macroinvertivores and grazers. Overall, these results suggest that the degree of change measured at coarse taxonomic levels masked high species-level turnover, although other potential explanations include that there was no impact of the storm, fish assemblages were impacted but underwent rapid recovery or that there is a time lag before the full impacts become apparent. This study confirms that in high-complexity, high diversity ecosystems such as coral reefs, species level analyses are essential to adequately capture the consequences of disturbance events. PMID:27285160

The Valencia trough and the origin of the western Mediterranean basins

NASA Astrophysics Data System (ADS)

Vegas, R.

1992-03-01

Evolutionary models for the Valencia trough must be necessarily related to the Neogene-Present geodynamics of the western Mediterranean basins. All these basins occupy new space created in the wake of the westward translation of the Alboran block and the counter-clockwise rotation of the Corso-Sardinian block. This escape-tectonics, microplate dispersal, model can account for the co-existence and progressive migration of compressional and extensional strain fields within the Africa-Europe broad zone of convergence. In this escape-tectonics model, the Valencia trough has resulted in a complex evolution which includes: (1) latest Oligocene-Early Miocene rifting along the Catalan-Valencian margin due to the opening of the Gulf of Lions; (2) almost simultaneous, Early Miocene, transpressive thrusting in the Balearic margin related to the initiation of displacement of the Alboran block; and (3) Late Miocene generalized extension as a consequence of the opening of the South Balearic basin.

Lower Miocene stratigraphy of the Gebel Shabrawet area, north Eastern desert Egypt

NASA Astrophysics Data System (ADS)

Abdelghany, Osman

2002-05-01

The Lower Miocene carbonate/siliciclastic sequence of the Shabrawet area, comprises a complex alternation of autochthonous and allogenic sediments. The sequence can be subdivided into two lithostratigraphic units. The lower unit (unit I) is equivalent to the Gharra Formation. It is mainly clastic and composed of sandstones, siltstones and shales with minor limestone intercalations. These sediments are rich in Clypeaster spp., Scutella spp., Miogypsina intermedia, Operculina complanata, and smaller foraminifera. The upper unit (unit II) was considered by previous workers as being equivalent to the Marmarica Formation. It consists mainly of non-clastic rocks, dominated by sandy and chalky limestones rich in larger foraminifera (miogypsinids and nummulitids). This unit is topped by a highly fossiliferous ( Heterostegina, Operculina and Planostegina) sandy limestone. The present study places both units in the Gharra Formation and reports for the first time M. intermedia from the Miocene sequence of the Shabrawet area.

Hierarchical drivers of reef-fish metacommunity structure.

PubMed

MacNeil, M Aaron; Graham, Nicholas A J; Polunin, Nicholas V C; Kulbicki, Michel; Galzin, René; Harmelin-Vivien, Mireille; Rushton, Steven P

2009-01-01

Coral reefs are highly complex ecological systems, where multiple processes interact across scales in space and time to create assemblages of exceptionally high biodiversity. Despite the increasing frequency of hierarchically structured sampling programs used in coral-reef science, little progress has been made in quantifying the relative importance of processes operating across multiple scales. The vast majority of reef studies are conducted, or at least analyzed, at a single spatial scale, ignoring the implicitly hierarchical structure of the overall system in favor of small-scale experiments or large-scale observations. Here we demonstrate how alpha (mean local number of species), beta diversity (degree of species dissimilarity among local sites), and gamma diversity (overall species richness) vary with spatial scale, and using a hierarchical, information-theoretic approach, we evaluate the relative importance of site-, reef-, and atoll-level processes driving the fish metacommunity structure among 10 atolls in French Polynesia. Process-based models, representing well-established hypotheses about drivers of reef-fish community structure, were assembled into a candidate set of 12 hierarchical linear models. Variation in fish abundance, biomass, and species richness were unevenly distributed among transect, reef, and atoll levels, establishing the relative contribution of variation at these spatial scales to the structure of the metacommunity. Reef-fish biomass, species richness, and the abundance of most functional-groups corresponded primarily with transect-level habitat diversity and atoll-lagoon size, whereas detritivore and grazer abundances were largely correlated with potential covariates of larval dispersal. Our findings show that (1) within-transect and among-atoll factors primarily drive the relationship between alpha and gamma diversity in this reef-fish metacommunity; (2) habitat is the primary correlate with reef-fish metacommunity structure at multiple spatial scales; and (3) inter-atoll connectedness was poorly correlated with the nonrandom clustering of reef-fish species. These results demonstrate the importance of modeling hierarchical data and processes in understanding reef-fish metacommunity structure.

Gear and survey efficiency of patent tongs for oyster populations on restoration reefs.

PubMed

Schulte, David M; Lipcius, Romuald N; Burke, Russell P

2018-01-01

Surveys of restored oyster reefs need to produce accurate population estimates to assess the efficacy of restoration. Due to the complex structure of subtidal oyster reefs, one effective and efficient means to sample is by patent tongs, rather than SCUBA, dredges, or bottom cores. Restored reefs vary in relief and oyster density, either of which could affect survey efficiency. This study is the first to evaluate gear (the first full grab) and survey (which includes selecting a specific half portion of the first grab for further processing) efficiencies of hand-operated patent tongs as a function of reef height and oyster density on subtidal restoration reefs. In the Great Wicomico River, a tributary of lower Chesapeake Bay, restored reefs of high- and low-relief (25-45 cm, and 8-12 cm, respectively) were constructed throughout the river as the first large-scale oyster sanctuary reef restoration effort (sanctuary acreage > 20 ha at one site) in Chesapeake Bay. We designed a metal frame to guide a non-hydraulic mechanical patent tong repeatedly into the same plot on a restored reef until all oysters within the grab area were captured. Full capture was verified by an underwater remotely-operated vehicle. Samples (n = 19) were taken on nine different reefs, including five low- (n = 8) and four high-relief reefs (n = 11), over a two-year period. The gear efficiency of the patent tong was estimated to be 76% (± 5% standard error), whereas survey efficiency increased to 81% (± 10%) due to processing. Neither efficiency differed significantly between young-of-the-year oysters (spat) and adults, high- and low-relief reefs, or years. As this type of patent tong is a common and cost-effective tool to evaluate oyster restoration projects as well as population density on fished habitat, knowing the gear and survey efficiencies allows for accurate and precise population estimates.

Coral reef evolution on rapidly subsiding margins

USGS Publications Warehouse

Webster, J.M.; Braga, J.C.; Clague, D.A.; Gallup, C.; Hein, J.R.; Potts, D.C.; Renema, W.; Riding, R.; Riker-Coleman, K.; Silver, E.; Wallace, L.M.

2009-01-01

A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2-6??m/ka) over the last 500??ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20??ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100-500??ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate changes, as well as a record of the response of coral reefs to these changes over the last six glacial cycles. ?? 2008 Elsevier B.V. All rights reserved.

Habitat degradation and fishing effects on the size structure of coral reef fish communities.

PubMed

Wilson, S K; Fisher, R; Pratchett, M S; Graham, N A J; Dulvy, N K; Turner, R A; Cakacaka, A; Polunin, N V C

2010-03-01

Overfishing and habitat degradation through climate change pose the greatest threats to sustainability of marine resources on coral reefs. We examined how changes in fishing pressure and benthic habitat composition influenced the size spectra of island-scale reef fish communities in Lau, Fiji. Between 2000 and 2006 fishing pressure declined in the Lau Islands due to declining human populations and reduced demand for fresh fish. At the same time, coral cover declined and fine-scale architectural complexity eroded due to coral bleaching and outbreaks of crown-of-thorns starfish, Acanthaster planci. We examined the size distribution of reef fish communities using size spectra analysis, the linearized relationship between abundance and body size class. Spatial variation in fishing pressure accounted for 31% of the variation in the slope of the size spectra in 2000, higher fishing pressure being associated with a steeper slope, which is indicative of fewer large-bodied fish and/or more small-bodied fish. Conversely, in 2006 spatial variation in habitat explained 53% of the variation in the size spectra slopes, and the relationship with fishing pressure was much weaker (approximately 12% of variation) than in 2000. Reduced cover of corals and lower structural complexity was associated with less steep size spectra slopes, primarily due to reduced abundance of fish < 20 cm. Habitat degradation will compound effects of fishing on coral reefs as increased fishing reduces large-bodied target species, while habitat loss results in fewer small-bodied juveniles and prey that replenish stocks and provide dietary resources for predatory target species. Effective management of reef resources therefore depends on both reducing fishing pressure and maintaining processes that encourage rapid recovery of coral habitat.

Habitat complexity and fish size affect the detection of Indo-Pacific lionfish on invaded coral reefs

NASA Astrophysics Data System (ADS)

Green, S. J.; Tamburello, N.; Miller, S. E.; Akins, J. L.; Côté, I. M.

2013-06-01

A standard approach to improving the accuracy of reef fish population estimates derived from underwater visual censuses (UVCs) is the application of species-specific correction factors, which assumes that a species' detectability is constant under all conditions. To test this assumption, we quantified detection rates for invasive Indo-Pacific lionfish ( Pterois volitans and P. miles), which are now a primary threat to coral reef conservation throughout the Caribbean. Estimates of lionfish population density and distribution, which are essential for managing the invasion, are currently obtained through standard UVCs. Using two conventional UVC methods, the belt transect and stationary visual census (SVC), we assessed how lionfish detection rates vary with lionfish body size and habitat complexity (measured as rugosity) on invaded continuous and patch reefs off Cape Eleuthera, the Bahamas. Belt transect and SVC surveys performed equally poorly, with both methods failing to detect the presence of lionfish in >50 % of surveys where thorough, lionfish-focussed searches yielded one or more individuals. Conventional methods underestimated lionfish biomass by ~200 %. Crucially, detection rate varied significantly with both lionfish size and reef rugosity, indicating that the application of a single correction factor across habitats and stages of invasion is unlikely to accurately characterize local populations. Applying variable correction factors that account for site-specific lionfish size and rugosity to conventional survey data increased estimates of lionfish biomass, but these remained significantly lower than actual biomass. To increase the accuracy and reliability of estimates of lionfish density and distribution, monitoring programs should use detailed area searches rather than standard visual survey methods. Our study highlights the importance of accounting for sources of spatial and temporal variation in detection to increase the accuracy of survey data from coral reef systems.

The Farther the Better: Effects of Multiple Environmental Variables on Reef Fish Assemblages along a Distance Gradient from River Influences.

PubMed

Neves, Leonardo M; Teixeira-Neves, Tatiana P; Pereira-Filho, Guilherme H; Araújo, Francisco G

2016-01-01

The conservation and management of site-attached assemblages of coastal reefs are particularly challenging because of the tremendous environmental variation that exists at small spatial scales. In this sense, understanding the primary sources of variation in spatial patterns of the biota is fundamental for designing effective conservation policies. We investigated spatial variation in fish assemblages around the windward and leeward sides of coastal islands situated across a gradient of riverine influence (13 km in length). Specifically, relationships between rocky reef fish assemblages and benthic, topographic and physical predictors were assessed. We hypothesized that river induced disturbances may overcome local habitat features in modeling spatial patterns of fish distribution. Fish assemblages varied primarily due to the strong directional gradient of riverine influence (22.6% of the estimated components of variation), followed by topographic complexity (15%), wave exposure (9.9%), and benthic cover (8%). The trophic structure of fish assemblages changed from having a high abundance of invertebrate feeders in macroalgae-dominated reefs close to river mouths to a high proportion of herbivores, planktivores and invertebrate feeder species in reefs with large boulders covered by epilithic algal matrices, as the distance from rivers increased. This gradient led to an increase of 4.5-fold in fish richness and fish trophic group diversity, 11-fold in fish biomass and 10-fold in fish abundance. Our results have implications for the conservation and monitoring of assemblages patchily distributed at small spatial scales. The major role of distance from river influences on fish assemblages rather than benthic cover and topographic complexity suggest that managing land-based activities should be a conservation priority toward reef restoration.

Seven new species of Paleanotus (Annelida: Chrysopetalidae) described from Lizard Island, Great Barrier Reef, and coral reefs of northern Australia and the Indo-Pacific: two cryptic species pairs revealed between western Pacific Ocean and the eastern Indian Ocean.

PubMed

Watson, Charlotte

2015-09-18

Morphological investigation into the paleate genus Paleanotus Schmarda 1861 of the family Chrysopetalidae from northern Australian coral reefs, primarily Lizard Island and outlying reefs, included a complex of very small, slender individuals (length < 5 mm). This complex resolved into 7 new species, described herein: Paleanotus inornatus n. sp., P. adornatus n. sp., P. chrysos n. sp., P. aquifolia n. sp., P. latifolia n. sp., P. silus n. sp., and P. silopsis n. sp. A key is provided to the new species and Paleanotus distinguished from Treptopale and Hyalopale, two closely related genera. Diagnostic features of the apical structure and shape of the notochaetal main paleae plus median paleae shape and raised rib pattern, differentiates each species from the other. Gametous states are described. Two cryptic species pairs (Paleanotus silopsis n. sp. and P. silus n. sp.; Paleanotus aquifolia n. sp. and P. latifolia n. sp.) were identified. In each case one species is restricted to either the NE or NW Australian coast. In each pair the most eastern point for the NW Australian species range occurs at Darwin, western Arnhemland, Northern Territory. Additional material for each species pair extends their respective ranges northwards: NW Australia to Thailand, Andaman Sea, eastern Indian Ocean or NE Australia, Great Barrier Reef to the Philippines, western Pacific Ocean. Cryptic morphology and potential genetic diversity is discussed in Paleanotus inornatus n. sp. and P. adornatus n. sp. that possess overlapping widespread distribution patterns across northern Australia and Indo-Pacific reefs. The smallest bodied taxon, Paleanotus chrysos n. sp. is the only species with a Coral Sea range encompassing Lizard Island, Heron Island and New Caledonia.

The Farther the Better: Effects of Multiple Environmental Variables on Reef Fish Assemblages along a Distance Gradient from River Influences

PubMed Central

Neves, Leonardo M.; Teixeira-Neves, Tatiana P.; Pereira-Filho, Guilherme H.; Araújo, Francisco G.

2016-01-01

The conservation and management of site-attached assemblages of coastal reefs are particularly challenging because of the tremendous environmental variation that exists at small spatial scales. In this sense, understanding the primary sources of variation in spatial patterns of the biota is fundamental for designing effective conservation policies. We investigated spatial variation in fish assemblages around the windward and leeward sides of coastal islands situated across a gradient of riverine influence (13 km in length). Specifically, relationships between rocky reef fish assemblages and benthic, topographic and physical predictors were assessed. We hypothesized that river induced disturbances may overcome local habitat features in modeling spatial patterns of fish distribution. Fish assemblages varied primarily due to the strong directional gradient of riverine influence (22.6% of the estimated components of variation), followed by topographic complexity (15%), wave exposure (9.9%), and benthic cover (8%). The trophic structure of fish assemblages changed from having a high abundance of invertebrate feeders in macroalgae-dominated reefs close to river mouths to a high proportion of herbivores, planktivores and invertebrate feeder species in reefs with large boulders covered by epilithic algal matrices, as the distance from rivers increased. This gradient led to an increase of 4.5-fold in fish richness and fish trophic group diversity, 11-fold in fish biomass and 10-fold in fish abundance. Our results have implications for the conservation and monitoring of assemblages patchily distributed at small spatial scales. The major role of distance from river influences on fish assemblages rather than benthic cover and topographic complexity suggest that managing land-based activities should be a conservation priority toward reef restoration. PMID:27907017

Geometry and evolution of low-angle normal faults (LANF) within a Cenozoic high-angle rift system, Thailand: Implications for sedimentology and the mechanisms of LANF development

NASA Astrophysics Data System (ADS)

Morley, Chris K.

2009-10-01

At least eight examples of large (5-35 km heave), low-angle normal faults (LANFs, 20°-30° dip) occur in the Cenozoic rift basins of Thailand and laterally pass into high-angle extensional fault systems. Three large-displacement LANFs are found in late Oligocene-Miocene onshore rift basins (Suphan Buri, Phitsanulok, and Chiang Mai basins), they have (1) developed contemporaneous with, or after the onset of, high-angle extension, (2) acted as paths for magma and associated fluids, and (3) impacted sedimentation patterns. Displacement on low-angle faults appears to be episodic, marked by onset of lacustrine conditions followed by axial progradation of deltaic systems that infilled the lakes during periods of low or no displacement. The Chiang Mai LANF is a low-angle (15°-25°), high-displacement (15-35 km heave), ESE dipping LANF immediately east of the late early Miocene Doi Inthanon and Doi Suthep metamorphic core complexes. Early Cenozoic transpressional crustal thickening followed by the northward motion of India coupled with Burma relative to east Burma and Thailand (˜40-30 Ma) caused migmatization and gneiss dome uplift in the late Oligocene of the core complex region, followed by LANF activity. LANF displacement lasted 4-6 Ma during the early Miocene and possibly transported a late Oligocene-early Miocene high-angle rift system 35 km east. Other LANFs in Thailand have lower displacements and no associated metamorphic core complexes. The three LANFs were initiated as low-angle faults, not by isostatic rotation of high-angle faults. The low-angle dips appear to follow preexisting low-angle fabrics (thrusts, shear zones, and other low-angle ductile foliations) predominantly developed during Late Paleozoic and early Paleogene episodes of thrusting and folding.

Mesophotic bioerosion: Variability and structural impact on U.S. Virgin Island deep reefs

NASA Astrophysics Data System (ADS)

Weinstein, David K.; Smith, Tyler B.; Klaus, James S.

2014-10-01

Mesophotic reef corals, found 30-150 m below sea level, build complex structures that provide habitats for diverse ecosystems. Whereas bioerosion is known to impact the development and persistence of shallow reef structures, little is known regarding the extent of mesophotic bioerosion or how it might affect deeper reef geomorphology and carbonate accretion. Originally pristine experimental coral substrates and collected coral rubble were both used to investigate the variation and significance of mesophotic coral reef bioerosion south of St. Thomas, U.S. Virgin Islands. Bioerosion rates were calculated from experimental coral substrates exposed as framework for 1 and 2 years at four structurally distinct mesophotic coral reef habitats (between 30 and 45 m) as well as at a mid-shelf patch reef (21 m) and a shallow fringing patch reef (9 m). The long-term effects of macroboring were assessed by examining coral rubble collected at all sites. Overall, differences in bioerosional processes were found between shallow and mesophotic reefs. Increases in bioerosion on experimental substrates (amount of weight lost) were related to both decreasing seawater depth and increasing biomass of bioeroding parrotfish. Significant differences in coral skeleton bioerosion rates were also found between the transitional mesophotic reef zone (30-35 m) and the upper mesophotic reef zone (35-50 m) after 2 years of exposure, ranging from - 19.6 to 3.7 g/year. Total coral rubble macroboring was greater at most deep sites compared to shallower sites. Bioerosional grazing was found to dominate initial substrate modification in reefs 30.7 m and shallower, but sponges are believed to act as the main time-averaged long-term substrate bioeroders in reefs between 35 and 50 m. Although initial substrate bioerosion rates of a uniform substrate were relatively homogeneous in the 35-50 m depth zone, comparison of site composition suggests that mesophotic bioerosion will vary depending on the amount, location, and type of available substrate, and the duration both coral rubble and in situ coral framework are exposed on the seafloor. These variations may exaggerate pronounced structural differences in mesophotic reef habitats that experience few other methods of erosion.

Coral reefs in an urban embayment in Hawaii: a complex case history controlled by natural and anthropogenic stress

NASA Astrophysics Data System (ADS)

Grigg, R. W.

1995-11-01

The effects of natural and anthropogenic stress need to be separated before coral reef ecosystems can be effectively managed. In this paper, a 25 year case history of coral reefs in an urban embayment (Mamala Bay) off Honolulu, Hawaii is described and differences between natural and man-induced stress are distinguished. Mamala Bay is a 30 km long shallow coastal bay bordering the southern (leeward) shore of Oahu and the city of Honolulu in the Hawaiian Islands. During the last 25 years, this area has been hit by two magnitude 5 hurricane events (winds > 240 km/h) generating waves in excess of 7.5 m. Also during this period, two large sewer outfalls have discharged up to 90 million gallons per day (mgd) or (360 × 106 L/day) of point source pollution into the bay. Initially the discharge was raw sewage, but since 1977 it has received advanced primary treatment. Non-point source run-off from the Honolulu watershed also enters the bay on a daily basis. The results of the study show that discharge of raw sewage had a serious but highly localized impact on shallow (˜10 m) reef corals in the bay prior to 1977. After 1977, when treatment was upgraded to the advanced primary level and outfalls were extended to deep water (> 65 m), impacts to reef corals were no longer significant. No measurable effects of either point or non-point source pollution on coral calcification, growth, species composition, diversity or community structure related to pollution can now be detected. Conversely the effects of hurricane waves in 1982 and 1992 together caused major physical destruction to the reefs. In 1982, average coral cover of well-developed offshore reefs dropped from 60-75% to 5-15%. Only massive species in high relief areas survived. Today, recovery is occurring, and notwithstanding major future disturbance events, long-term biological processes should eventually return the coral ecosystems to a more mature successional stage. This case history illustrates the complex nature of the cumulative effects of natural and anthropogenic stress on coral reefs and the need for a long-term data base before the status of a coral reef can be properly interpreted.

Eddy covariance measurement of the spatial heterogeneity of surface energy exchanges over Heron Reef, Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

MacKellar, M.; McGowan, H. A.; Phinn, S. R.

2011-12-01

Coral reefs cover 2.8 to 6.0 x 105 km2 of the Earth's surface and are warm, shallow regions that are believed to contribute enhanced sensible and latent heat to the atmosphere, relative to the surrounding ocean. To predict the impact of climate variability on coral reefs and their weather and climate including cloud, winds, rainfall patterns and cyclone genesis, accurate parameterisation of air-sea energy exchanges over coral reefs is essential. This is also important for the parameterisation and validation of regional to global scale forecast models to improve prediction of tropical and sub-tropical marine and coastal weather. Eddy covariance measurements of air-sea fluxes over coral reefs are rare due to the complexities of installing instrumentation over shallow, tidal water. Consequently, measurements of radiation and turbulent flux data for coral reefs have been captured remotely (satellite data) or via single measurement sites downwind of coral reefs (e.g. terrestrial or shipboard instrumentation). The resolution of such measurements and those that have been made at single locations on reefs may not capture the spatial heterogeneity of surface-atmosphere energy exchanges due to the different geomorphic and biological zones on coral reefs. Accordingly, the heterogeneity of coral reefs with regard to substrate, benthic communities and hydrodynamic processes are not considered in the characterization of the surface radiation energy flux transfers across the water-atmosphere interface. In this paper we present a unique dataset of concurrent in situ eddy covariance measurements made on instrumented pontoons of the surface energy balance over different geomorphic zones of a coral reef (shallow reef flat, shallow and deep lagoons). Significant differences in radiation transfers and air-sea turbulent flux exchanges over the reef were highlighted, with higher Bowen ratios over the shallow reef flat. Increasing wind speed was shown to increase flux divergence between sites to the extent that under unstable, south-easterly Trade Winds the net flux of heat was positive and negative over different geomorphic zones. The surface drag coefficient ranged from 1 to 2.5 x 10-3, with no significant difference between sites. Results highlight the spatial variation of air-sea energetics across a lagoonal platform reef in response to local meteorology, hydrodynamics and benthic/substrate cover.

Spatial and Seasonal Calcification in Corals and Calcareous Crusts in a Naturally Warm Coral Reef Region

NASA Astrophysics Data System (ADS)

Roik, A.; Roder, C.; Roethig, T.; Voolstra, C. R.

2016-02-01

The Red Sea harbors highly diverse and structurally complex coral reefs and is of interest for ocean warming studies. In the central and southern part, water temperatures rise above 30°C during summer, constituting one of the warmest coral reef environments worldwide. Additionally, seasonal variability of temperatures allows studying changes of environmental conditions and their effects on coral reef processes. To explore the influence of these warm and seasonally variable habitats on reef calcification, we measured in situ calcification of primary and secondary reef-builders in the central Red Sea. We collected calcification rates on the major habitat-forming coral genera Porites, Acropora, and Pocillopora, and also on calcareous crusts (CC). The study comprised forereef and backreef environments of three reefs along a cross-shelf gradient assessed over four seasons of the year. Calcification patterns of all coral genera were consistent across the shelf and highest in spring. In contrast to the corals, CC calcification strongly increased with distance from shore, but varied to a lesser extend over the seasons demonstrating lower calcification rates during spring and summer. Interestingly, reef calcification rates in the central Red Sea were on average in the range of data reported from the Caribbean and Indo-Pacific. For Acropora, annual average calcification rates were even at the lower end in comparison to studies from other locations. While coral calcification maxima typically have been observed during summer in many reef locations worldwide, we observed calcification maxima during spring in the central Red Sea indicating that summer temperatures may exceed the optima of reef calcifiers. Our study provides a baseline of calcification data for the region and serves as a foundation for comparative efforts to quantify the impact of future environmental change.

Modeling fine-scale coral larval dispersal and interisland connectivity to help designate mutually-supporting coral reef marine protected areas: Insights from Maui Nui, Hawaii

USGS Publications Warehouse

Storlazzi, Curt; van Ormondt, Maarten; Chen, Yi-Leng; Elias, Edwin P. L.

2017-01-01

Connectivity among individual marine protected areas (MPAs) is one of the most important considerations in the design of integrated MPA networks. To provide such information for managers in Hawaii, USA, a numerical circulation model was developed to determine the role of ocean currents in transporting coral larvae from natal reefs throughout the high volcanic islands of the Maui Nui island complex in the southeastern Hawaiian Archipelago. Spatially- and temporally-varying wind, wave, and circulation model outputs were used to drive a km-scale, 3-dimensional, physics-based circulation model for Maui Nui. The model was calibrated and validated using satellite-tracked ocean surface current drifters deployed during coral-spawning conditions, then used to simulate the movement of the larvae of the dominant reef-building coral, Porites compressa, from 17 reefs during eight spawning events in 2010–2013. These simulations make it possible to investigate not only the general dispersal patterns from individual coral reefs, but also how anomalous conditions during individual spawning events can result in large deviations from those general patterns. These data also help identify those reefs that are dominated by self-seeding and those where self-seeding is limited to determine their relative susceptibility to stressors and potential roadblocks to recovery. Overall, the numerical model results indicate that many of the coral reefs in Maui Nui seed reefs on adjacent islands, demonstrating the interconnected nature of the coral reefs in Maui Nui and providing a key component of the scientific underpinning essential for the design of a mutually supportive network of MPAs to enhance conservation of coral reefs.

LiDAR as an Exploration Tool

DOE Data Explorer

Boschmann, D.; Diles, J.; Clarno, J.; Meigs, A.; Walsh, P.

2011-01-01

Using LiDAR to identify structural and volcanic evolution of a Miocene-Pleistocene age bimodal volcanic complex and implications for geothermal potential. The file includes an updated geologic map, methods, and preliminary results.

Provenance of the lower Miocene of the Gulf of Mexico from detrital zircon double dating

NASA Astrophysics Data System (ADS)

xu, J.

2013-12-01

The lower Miocene interval of the Gulf of Mexico (GOM) has recently gained increasing attention from oil and gas industry due to its hydrocarbon potential below the salt canopy. However, it has been less well studied than both the underlying Oligocene and overlying middle Miocene strata. The lower Miocene worldwide is a transitional period of tectonic, climatic, and oceanographic change. In particular, it is a period of major tectonic reorganization in the western interior of North America (Rocky Mountains), involving a shift from the Oligocene thermal phase, with abundant volcanic activity recorded in the thick Frio/Vicksburg succession of the GOM, to the Miocene Basin-Range extensional phase. Climatic conditions also changed from a relatively arid Oligocene to wetter Miocene, resulting in increased sediment yields from exhumed tectonic structures. Previous provenance studies used proportions of quartz, feldspar and lithic fragments and consideration of likely river courses through known paleogeomorphological elements. Only limited detrital zircon (DZ) U-Pb studies on Paleocene strata have been undertaken and there has been no previous U-Pb and (U-Th)/He double dating in the GOM. In this study we apply the latest analytical approaches, such as DZ U-Pb dating to gain robust source terranes ages and more fully elucidate the complex sediment provenance and dispersal history of GOM. We also employ DZ (U-Th)/He (ZHe) dating, combined with DZ U-Pb, to not only define sedimentary provenance but also the exhumation histories of detrital source regions. Samples of lower Miocene outcrop exposures in Texas and Louisiana have been collected to discriminate the varied tectonic and drainage system changes across the basin in lateral. In addition, samples from the Eocene, Oligocene and middle Miocene have been obtained to reveal vertical shift of source terranes contributions. Our initial age data show detrital zircons of lower Miocene sediments come from a wide range of source terranes including a large populations from the western interior of North America (Rocky Mountains), Grenville, Mid-Continent, and Yavapai-Mazatzal provinces, with smaller populations from the Appalachian-Ouachita, Wyoming or Superior regions. Based on U-Pb dating results, we will carry out (U-Th)/He dating on selected zircons to reveal the detailed exhumation histories of the sediment source regions. Using the dual criteria of DZ crystallization age (U-Pb) and cooling age (U-Th/He) to constrain provenance will enable us to generate rigorous reconstructions of the lower Miocene depositional systems from source terrane to deep-water sink for this key transitional period in geologic history.

Origin of Silurian reefs in the Alexander Terrane of southeastern Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soja, C.M.

1991-04-01

Lower to Upper Silurian (upper Llandovery-Ludlow) limestones belonging to the Heceta Formation record several episodes of reef growth in the Alexander terrane of southeastern Alaska. As the oldest carbonates of wide-spread distribution in the region, the Heceta limestones represent the earliest development of a shallow-marine platform within the Alexander arc and the oldest foundation for reef evolution. These deposits provide important insights into the dynamic processes, styles, and bathymetry associated with reef growth in tectonically active oceanic islands. Massive stromatoporoids, corals, and red algae are preserved in fragmental rudstones and represent a fringing reef that formed at the seaward edgemore » of the incipient marine shelf. Accessory constituents in this reef include crinoids and the cyanobacterium Girvanella. Small biostromes were constructed by ramose corals and stromatoporoids on oncolitic substrates in backreef or lagoonal environments. These buildups were associated with low-diversity assemblages of brachiopods and with gastropods, amphiporids, calcareous algae and cyanobacteria. Microbial boundstones reflect the widespread encrustation of cyanobacteria and calcified microproblematica on shelly debris as stromatolitic mats that resulted in the development of a stromatactoid-bearing mud mound and a barrier reef complex. Epiphytaceans, other microbes, and aphrosalpingid sponges were the primary frame-builders of the barrier reefs. These buildups attained significant relief at the shelf margin and shed detritus as slumped blocks and debris flows into deep-water sites along the slope. The similarity of these stromatolitic-aphrosalpingid reefs to those from Siluro-Devonian strata of autochthonous southwestern Alaska suggests paleobiogeographic ties of the Alexander terrane to cratonal North America during the Silurian.« less

Movement patterns of silvertip sharks ( Carcharhinus albimarginatus) on coral reefs

NASA Astrophysics Data System (ADS)

Espinoza, Mario; Heupel, Michelle. R.; Tobin, Andrew J.; Simpfendorfer, Colin A.

2015-09-01

Understanding how sharks use coral reefs is essential for assessing risk of exposure to fisheries, habitat loss, and climate change. Despite a wide Indo-Pacific distribution, little is known about the spatial ecology of silvertip sharks ( Carcharhinus albimarginatus), compromising the ability to effectively manage their populations. We examined the residency and movements of silvertip sharks in the central Great Barrier Reef (GBR). An array of 56 VR2W acoustic receivers was used to monitor shark movements on 17 semi-isolated reefs. Twenty-seven individuals tagged with acoustic transmitters were monitored from 70 to 731 d. Residency index to the study site ranged from 0.05 to 0.97, with a mean residency (±SD) of 0.57 ± 0.26, but most individuals were detected at or near their tagging reef. Clear seasonal patterns were apparent, with fewer individuals detected between September and February. A large proportion of the tagged population (>71 %) moved regularly between reefs. Silvertip sharks were detected less during daytime and exhibited a strong diel pattern in depth use, which may be a strategy for optimizing energetic budgets and foraging opportunities. This study provides the first detailed examination of the spatial ecology and behavior of silvertip sharks on coral reefs. Silvertip sharks remained resident at coral reef habitats over long periods, but our results also suggest this species may have more complex movement patterns and use larger areas of the GBR than common reef shark species. Our findings highlight the need to further understand the movement ecology of silvertip sharks at different spatial and temporal scales, which is critical for developing effective management approaches.

Ecological characteristics of coral patch reefs at Midway Atoll, Northwestern Hawaiian Islands

USGS Publications Warehouse

Schroeder, R.E.; Parrish, J.D.

2006-01-01

Ecological aspects of coral patch reefs were studied from 1981 to 1985 in Welles Harbor, Midway Atoll. Water temperatures varied from 17??C in February to 28??C in August. Sizes of reefs studied were described by mean area (59 m2), mean volume (52 m3), vertical relief (<1 m), and inter-reef isolation (100 m). Considerable temporal change in reef size occurred due to large winter swells shifting bottom sand. Six common species accounted for 70% of all individual fish visually censused over 4 years. Overall fish assemblage composition ranged from 11 to 46 fish/10 m2, from 3 to 14 species. Numerical abundance and species richness for all fish (pooled) strongly correlated with physical reef substrate characteristics of area, volume, and vertical relief during summer. Species diversity (H') was not correlated with the substrate variables, suggesting similarity in the structure of fish communities among different sizes of patch reefs. Daily surveillance for presence of large transient taxa suggested that visits by sharks, large jacks, monk seals, sea turtles, and dolphins were infrequent. Density estimates were made for all conspicuous invertebrate megafauna during initial and final assessments. Six common taxa provided 90% of these counts; nearly half were sea urchins. Percent cover also was recorded for coral and algal species on the patch reefs. Cover by live coral was low (about 7%) and dominated by a few species. Mean algal cover ranged from 32 to 77%. Such information on ecological characteristics of reefs may aid in understanding complex ecological processes and provides an earlier reference for current ecosystem studies.

Evidence of Lake Trout reproduction at Lake Michigan's mid-lake reef complex

USGS Publications Warehouse

Janssen, J.; Jude, D.J.; Edsall, T.A.; Paddock, R.W.; Wattrus, N.; Toneys, M.; McKee, P.

2006-01-01

The Mid-Lake Reef Complex (MLRC), a large area of deep (> 40 m) reefs, was a major site where indigenous lake trout (Salvelinus namaycush) in Lake Michigan aggregated during spawning. As part of an effort to restore Lake Michigan's lake trout, which were extirpated in the 1950s, yearling lake trout have been released over the MLRC since the mid-1980s and fall gill net censuses began to show large numbers of lake trout in spawning condition beginning about 1999. We report the first evidence of viable egg deposition and successful lake trout fry production at these deep reefs. Because the area's existing bathymetry and habitat were too poorly known for a priori selection of sampling sites, we used hydroacoustics to locate concentrations of large fish in the fall; fish were congregating around slopes and ridges. Subsequent observations via unmanned submersible confirmed the large fish to be lake trout. Our technological objectives were driven by biological objectives of locating where lake trout spawn, where lake trout fry were produced, and what fishes ate lake trout eggs and fry. The unmanned submersibles were equipped with a suction sampler and electroshocker to sample eggs deposited on the reef, draw out and occasionally catch emergent fry, and collect egg predators (slimy sculpin Cottus cognatus). We observed slimy sculpin to eat unusually high numbers of lake trout eggs. Our qualitative approaches are a first step toward quantitative assessments of the importance of lake trout spawning on the MLRC.

Structural elements of the Sulu Sea, Philippines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinz, K.; Block, M.; Kudrass, H.R.

1994-07-01

The structure and tectonic history of the Sulu Sea are described on the basis of seismic reflection data combined with the findings of onshore and offshore geological studies, and the results of ODP Leg 124 drilling. Closing of a hypothetical Mesozoic proto-South China Sea associated with the formation of oceanic crustal splinters in the late Eocene followed by southward subduction and, in turn, progressive collision of the north Palawan continental terrane with the micro-continental Borneo plate since the middle Miocene, resulted in the formation of the structurally complex Sulu-Borneo collision belt. The latter comprises north Sabah, southern and central Palawan,more » and the northwest Sulu basin. Fracturing of the Borneo micro-continental plate into the Sulu and Cagayan ridges initiated the opening of the southeast Sulu basin during the late Oligocene through the early Miocene. Collision of the north Palawan continental terrane with Cagayan Ridge in the late early Miocene and oblique collision of these blocks with the central Philippines resulted in the still ongoing closing of the southeast Sulu basin since the middle or late Miocene. Closing of the southeast Sulu basin began with the formation of an oceanic crustal slab.« less

Palynostratigraphy, palaeoclimates and palaeodepositional environments of the Miocene aged Agbada Formation in the Niger Delta, Nigeria

NASA Astrophysics Data System (ADS)

Bankole, Samson I.; Schrank, Eckart; Osterloff, Peter L.

2014-07-01

A diverse assemblage of palynomorphs dominated by terrestrially derived pollen and spores is reported from three wells penetrating the Miocene Agbada Formation. The pteridophyte and bryophyte spores which form the background assemblages in the three wells are good indicators of humid tropical climates which might have prevailed in the Niger Delta during the Miocene. The abundance and variations of climate-sensitive taxa including mangrove affiliated pollen and spore types Acrostichumsporites, Psilatricolporites crassus, Zonocostites ramonae and Graminidites annulatus representing the savannah vegetation cover indicate a complex interplay between periods of wetter and drier climates. Marine-derived dinoflagellate cysts and foraminiferal test linings are significantly present in the three wells. Taxa indicating freshwater contributions including Botryococcus spp., Chomotriletes minor, Ovoidites parvus and Pediastrum spp. are also represented numerically across the three wells. The presence of age diagnostic palynomorphs such as Crassoretitriletes vanraadshooveni, Retibrevitricolporites obodoensis, Tuberculodinium vancampoae, Zonocostites ramonae and Tuberculodinium vancampoae recovered in the three sections studied suggest a Miocene age for the investigated Agbada Formation. The proposed age is supported by the ranges of key palynomorphs in contemporaneous basins in Africa, northern South America and other parts of the World.

Semi-automated fault system extraction and displacement analysis of an excavated oyster reef using high-resolution laser scanned data

NASA Astrophysics Data System (ADS)

Molnár, Gábor; Székely, Balázs; Harzhauser, Mathias; Djuricic, Ana; Mandic, Oleg; Dorninger, Peter; Nothegger, Clemens; Exner, Ulrike; Pfeifer, Norbert

2015-04-01

In this contribution we present a semi-automated method for reconstructing the brittle deformation field of an excavated Miocene oyster reef, in Stetten, Korneuburg Basin, Lower Austria. Oyster shells up to 80 cm in size were scattered in a shallow estuarine bay forming a continuous and almost isochronous layer as a consequence of a catastrophic event in the Miocene. This shell bed was preserved by burial of several hundred meters of sandy to silty sediments. Later the layers were tilted westward, uplifted and erosion almost exhumed them. An excavation revealed a 27 by 17 meters area of the oyster covered layer. During the tectonic processes the sediment volume suffered brittle deformation. Faults mostly with some centimeter normal component and NW-SE striking affected the oyster covered volume, dissecting many shells and the surrounding matrix as well. Faults and displacements due to them can be traced along the site typically at several meters long, and as fossil oysters are broken and parts are displaced due to the faulting, along some faults it is possible to follow these displacements in 3D. In order to quantify these varying displacements and to map the undulating fault traces high-resolution scanning of the excavated and cleaned surface of the oyster bed has been carried out using a terrestrial laser scanner. The resulting point clouds have been co-georeferenced at mm accuracy and a 1mm resolution 3D point cloud of the surface has been created. As the faults are well-represented in the point cloud, this enables us to measure the dislocations of the dissected shell parts along the fault lines. We used a semi-automatic method to quantify these dislocations. First we manually digitized the fault lines in 2D as an initial model. In the next step we estimated the vertical (i.e. perpendicular to the layer) component of the dislocation along these fault lines comparing the elevations on two sides of the faults with moving averaging windows. To estimate the strike-slip dislocation component, the surface points of the dissected shells on both sides of the fault planes were compared and displacement vectors were derived. The exact orientation of the fault planes cannot be accurately extracted automatically, so the distinction between normal and reverse fault is difficult. This makes the third component of the dislocation to be estimated inaccurately. These derived dislocation values are regarded as components of the dislocation vectors and were transformed back to the real world spatial coordinate system. Interpolating these dislocation vectors along fault lines we calculated and visualized the deformation field along the whole surface of the oyster reef. Although this deformation field is only a 2D section of the real 3D deformation field, its elaboration reveals the spatial variability of the deformation according to sediment inhomogeneity. The project is supported by the Austrian Science Fund (FWF P 25883-N29).

Geology and hydrogeology of the Caribbean islands aquifer system of the Commonwealth of Puerto Rico and the U.S. Virgin Islands

USGS Publications Warehouse

Renken, Robert A.; Ward, W. C.; Gill, I.P.; Gómez-Gómez, Fernando; Rodríguez-Martínez, Jesús; ,

2002-01-01

Poorly lithified to unconsolidated carbonate and clastic sedimentary rocks of Tertiary (Oligocene to Pliocene) and Quaternary (Pleistocene to Holocene) age compose the South Coast aquifer and the North Coast limestone aquifer system of Puerto Rico; poorly lithified to unlithified carbonate rocks of late Tertiary (early Miocene to Pliocene) age make up the Kingshill aquifer of St. Croix, U.S. Virgin Islands. The South Coast aquifer, North Coast limestone aquifer system, and Kingshill aquifer are the most areally extensive and function as the major sources of ground water in the U.S. Caribbean Islands Regional Aquifer-System Analysis (CI-RASA) study area. In Puerto Rico's South Coast ground-water province, more than 1,000 meters of clastic and carbonate rocks of Oligocene to Pliocene age infill the South Coast Tertiary Basin. The pattern of lithofacies within this basin appears to have been controlled by changes in base level that were, at times, dominated by tectonic movement (uplift and subsidence), but were also influenced by eustasy. Deposition of the 70-kilometer long and 3- to 8-kilometer wide fan-delta plain that covers much of the South Coast ground-water province occurred largely in response to glacially-induced changes in sea level and climate during the Quaternary period. Tectonic movement played a much less important role during the Quaternary. The North Coast ground-water province of Puerto Rico is underlain by homoclinal coastal plain wedge of carbonate and siliciclastic rocks that infill the North Coast Tertiary Basin and thicken to more than 1,700 meters. A thin basal siliciclastic sequence of late Oligocene age is overlain by a thick section of mostly carbonate rocks of Oligocene to middle Miocene age. Globigerinid limestone of late Miocene to Pliocene age crops out and lies in the shallow subsurface areas of northwestern Puerto Rico. Oligocene to middle Miocene age rocks tentatively can be divided into five depositional sequences and associated systems tracts; these rocks record carbonate and minor siliciclastic deposition that occurred in response to changes in relative sea level. The Cibao Formation represents the most complex of these sequences and contains a varied facies of carbonate, mixed carbonate-siliciclastic, and siliciclastic rocks that reflect differential uplift, subsidence, and transgression of the sea. Uplift, graben formation, and gradual shallowing of the sea are reflected within the bathyal-dominated sedimentary facies of the Kingshill Limestone in St. Croix, U.S. Virgin Islands. Reef-tract limestone beds of Pliocene age were subject to exposure, resubmergence, and meteoric leaching of aragonitic skeletal debris; these beds contain patchy lenses of dolomite that are restricted to a small, structurally-controlled embayment. The South Coast aquifer, the principal water-bearing unit of Puerto Rico's South Coast ground-water province, consists of boulder- to silt-size detritus formed by large and small coalescing fan deltas of Pleistocene to Holocene age. Deep well data indicates that it is possible to vertically separate and group a highly complex and irregular-bedded detrital sequence that underlies distal parts of the fan-delta plain into discrete water-bearing units if correlated with 30- to 40-meter thick, eustatically-controlled depositional cycles. Lithofacies maps show that greatest hydraulic conductivity within the fan-delta plain is generally associated with proximal fan and midfan areas. Distal and interfan areas are least permeable. Alluvial valley aquifers located in the western part of the South Coast ground-water province are important local sources of water supply and appear to contain some of the same physical and hydraulic characteristics as the South Coast aquifer. Older sedimentary rocks within the basin are poor aquifers; conglomeratic beds are well-cemented, and carbonate beds do not contain well-developed solution features, except locally where the beds are over

A long-living species of the hydrophiloid beetles: Helophorus sibiricus from the early Miocene deposits of Kartashevo (Siberia, Russia)

PubMed Central

Fikáček, Martin; Prokin, Alexander; Angus, Robert B.

2011-01-01

Abstract The recent hydrophiloid species Helophorus (Gephelophorus) sibiricus (Motschulsky, 1860) is recorded from the early Miocene deposits of Kartashevo assigned to the Ombinsk Formation. A detailed comparison with recent specimens allowed a confident identification of the fossil specimen, which is therefore the oldest record of a recent species for the Hydrophiloidea. The paleodistribution as well as recent distribution of the species is summarized, and the relevance of the fossil is discussed. In addition, the complex geological settings of the Kartashevo area are briefly summarized. PMID:22259280

Karst development and speleogenesis, Isla de Mona, Puerto Rico

USGS Publications Warehouse

Frank, E.F.; Mylroie, J.; Troester, J.; Alexander, E.C.; Carew, J.L.

1998-01-01

Isla de Mona consists of a raised table-top Miocene-Pliocene reef platform bounded on three sides by vertical cliffs, up to 80 m high. Hundreds of caves ring the periphery of the island and are preferentially developed in, but not limited to, the Lirio Limestone/Isla de Mona Dolomite contact. These flank margin caves originally formed at sea level and are now exposed at various levels by tectonic uplift of the island (Franbk 1983; Mylroie et al. 1995b). Wall cusps, a characteristic feature of flank margin caves, are ubiquitois features. Comparisons among similar caves formed in the Bahamas and Isla de Mona reveal the same overall morphology throughout the entire range of sizes and complexities. The coincidence of the primary cave development zone with the Lirio Limestone/Isla de Mona Dolomite contact may result from syngenetic speleogenesis and dolomitization rather than preferential dissolution along a lithologic boundary. Tectonic uplift and glacioeustatic sea level fluctuations produced caves at a variety of elevations. Speleothem dissolution took place in many caves under phreatic conditions, evidence these caves were flooded after an initial period of subaerial exposure and speleothem growth. Several features around the perimeter of the island are interpreted to be caves whose roofs were removed by surficial denudation processes. Several large closed depressions and dense pit cave fields are further evidence of surficial karst features. The cliff retreat around the island perimeter since the speleogenesis of the major cave systems is small based upon the distribution of the remnant cave sections.

Miocene volcanism in the Oaş-Gutâi Volcanic Zone, Eastern Carpathians, Romania: Relationship to geodynamic processes in the Transcarpathian Basin

NASA Astrophysics Data System (ADS)

Kovacs, Marinel; Seghedi, Ioan; Yamamoto, Masatsugu; Fülöp, Alexandrina; Pécskay, Zoltán; Jurje, Maria

2017-12-01

We present the first comprehensive study of Miocene volcanic rocks of the Oaş-Gutâi Volcanic Zone (OGVZ), Romania, which are exposed in the eastern Transcarpathian Basin (TB), within the Eastern Alpine-Western Carpathian-Northern Pannonian (ALCAPA) block. Collision between the ALCAPA block and Europe at 18-16 Ma produced the Carpathian fold-and-thrust belt. This was followed by clockwise rotation and an extensional regime forming core complexes of the separated TB fragment. Based on petrographic and geochemical data, including Srsbnd Nd isotopic compositions and Ksbnd Ar ages, we distinguish three types of volcanic activity in the OGVZ: (1) early Miocene felsic volcanism that produced caldera-related ignimbrites in the Gutâi Mountains (15.4-14.8 Ma); (2) widespread middle-late Miocene intermediate/andesitic volcanism (13.4-7.0 Ma); and (3) minor late Miocene andesitic/rhyolitic volcanism comprising the Oraşu Nou rhyolitic volcano and several andesitic-dacitic domes in the Oaş Mountains (11.3-9.5 Ma). We show that magma evolution in the OGVZ was controlled by assimilation-fractional crystallization and magma-mixing processes within an interconnected multi-level crustal magmatic reservoir. The evolution of volcanic activity within the OGVZ was controlled by the geodynamics of the Transcarpathian Basin. The early felsic and late intermediate Miocene magmas were emplaced in a post-collisional setting and were derived from a mantle source region that was modified by subduction components (dominantly sediment melts) and lower crust. The style of volcanism within the eastern TB system exhibits spatial variations, with andesitic composite volcanoes (Gutâi Mountains) observed at the margins, and isolated andesitic-rhyolitic monogenetic volcanoes (Oaş Mountains) in the center of the basin.

Hydrodynamic observations in support of Moored Autonomous pCO2 buoy efforts at La Parguera Marine Reserve

NASA Astrophysics Data System (ADS)

Rodriguez-Abudo, S.; Melendez, M.; Morell, J. M.; Padilla, A.; Salisbury, J.

2016-02-01

Time series of near-reef carbonate chemistry obtained through the National Coral Reef Monitoring Program (NCRMP) at La Parguera Marine Reserve, Puerto Rico exhibit seasonal and diurnal variations modulated by diverse processes including coral community metabolism, thermodynamics and hydrodynamics. While surface CO2 dynamics have been fairly well characterized with moored pCO2 efforts, detailed hydrodynamic information resulting from La Parguera's complex morphological, meteorological, and oceanographic processes is currently lacking. This project focuses on a one-month-long hydrodynamic assessment near a fore reef site located within 100 m of the NCRMP pCO2 buoy. Current profiles spanning 12 m of depth were resolved with a bottom-mounted ADCP. Preliminary results show that under no wind conditions, dominant currents are tidally driven and aligned with the reef channel. Depth-averaged currents exhibit diurnal and semidiurnal peaks, not inconsistent with tidal and wind forcing. The analysis also shows that at times surface current direction can differ from near-reef currents by as much as 200 degrees, suggesting a possible mismatch between carbonate chemistry resolved at the surface and that felt by the reef structure. Moreover, buoy measurements are potentially resolving carbonate chemistry from both, oceanic and inshore water masses. Our findings suggest that monitoring and potentially predicting near-reef CO2 dynamics require interdisciplinary expertise and integrated approaches. This project provides new insights into the effects of tidal and meteorological forcing on the carbonate chemistry of near-reef coral ecosystems.

A Biophysical Model for Hawaiian Coral Reefs: Coupling Local Ecology, Larval Transport and Climate Change

NASA Astrophysics Data System (ADS)

Kapur, M. R.

2016-02-01

Simulative models of reef ecosystems have been used to evaluate ecological responses to a myriad of disturbance events, including fishing pressure, coral bleaching, invasion by alien species, and nutrient loading. The Coral Reef Scenario Evaluation Tool (CORSET), has been developed and instantiated for both the Meso-American Reef (MAR) and South China Sea (SCS) regions. This model is novel in that it accounts for the many scales at which reef ecosystem processes take place; is comprised of a "bottom-up" structure wherein complex behaviors are not pre-programmed, but emergent and highly portable to new systems. Local-scale dynamics are coupled across regions through larval connectivity matrices, derived sophisticated particle transport simulations that include key elements of larval behavior. By this approach, we are able to directly evaluate some of the potential consequences of larval connectivity patterns across a range of spatial scales and under multiple climate scenarios. This work develops and applies the CORSET (Coral Reef Scenario Evaluation Tool) to the Main Hawaiian Islands under a suite of climate and ecological scenarios. We introduce an adaptation constant into reef-building coral dynamics to simulate observed resiliencies to bleaching events. This presentation will share results from the model's instantiation under two Resource Concentration Pathway climate scenarios, with emphasis upon larval connectivity dynamics, emergent coral tolerance to increasing thermal anomalies, and patterns of spatial fishing closures. Results suggest that under a business-as-usual scenario, thermal tolerance and herbivore removal will have synergistic effects on reef resilience.

Does high diurnal variability in a reef flat from Ofu, American Samoa confer resistance to ocean acidification?

NASA Astrophysics Data System (ADS)

Koweek, D.; Samuel, L.; Mucciarone, D. A.; Woodson, C. B.; Monismith, S. G.; Dunbar, R. B.

2012-12-01

Forecasts for coral reefs under various ocean acidification scenarios are becoming increasingly complex due to significant inter-site variability in biogeochemistry, ecology, and physical oceanography. The reef flats of Ofu, American Samoa are a potential end-member of this vulnerability spectrum due to extremely high diurnal variability in their biogeochemistry. Here we present coupled biogeochemical and physical oceanographic measurements from a shallow reef flat on Ofu in November 2011. We observed diurnal temperature ranges of up to 7°C, along with diurnal pH and dissolved oxygen ranges of 0.6 units, and 160 percent of saturation, respectively. Carbon system measurements were less extreme. Alkalinity varied between 2240-2360 μmol/kg and total dissolved inorganic carbon (TDIC) ranged between 1850-2100 μmol/kg during the diurnal cycle. These observations suggest diurnal ranges of ~240ppm CO2 and 1.5 units of ΩAr. The larger diurnal range in TDIC relative to alkalinity suggests a reef environment dominated by photosynthesis. From these observations, we explore the balance between the dominant biogeochemical processes of production and calcification on the reef flat in more detail, along with its implication for conferring resistance to ocean acidification. We use calcification rate estimates to provide insight to patterns of day and night growth and/or dissolution on the reef. Finally, we present evidence of tidal modulation of the biogeochemical signals and discuss the role of localized physical circulation in helping to determine a reef's vulnerability to ocean acidification.

Habitat degradation negatively affects auditory settlement behavior of coral reef fishes

PubMed Central

Harding, Harry R.; Wong, Kathryn E.; Merchant, Nathan D.; Meekan, Mark G.; Radford, Andrew N.; Simpson, Stephen D.

2018-01-01

Coral reefs are increasingly degraded by climate-induced bleaching and storm damage. Reef recovery relies on recruitment of young fishes for the replenishment of functionally important taxa. Acoustic cues guide the orientation, habitat selection, and settlement of many fishes, but these processes may be impaired if degradation alters reef soundscapes. Here, we report spatiotemporally matched evidence of soundscapes altered by degradation from recordings taken before and after recent severe damage on Australia’s Great Barrier Reef. Postdegradation soundscapes were an average of 15 dB re 1 µPa quieter and had significantly reduced acoustic complexity, richness, and rates of invertebrate snaps compared with their predegradation equivalents. We then used these matched recordings in complementary light-trap and patch-reef experiments to assess responses of wild fish larvae under natural conditions. We show that postdegradation soundscapes were 8% less attractive to presettlement larvae and resulted in 40% less settlement of juvenile fishes than predegradation soundscapes; postdegradation soundscapes were no more attractive than open-ocean sound. However, our experimental design does not allow an estimate of how much attraction and settlement to isolated postdegradation soundscapes might change compared with isolated predegradation soundscapes. Reductions in attraction and settlement were qualitatively similar across and within all trophic guilds and taxonomic groups analyzed. These patterns may lead to declines in fish populations, exacerbating degradation. Acoustic changes might therefore trigger a feedback loop that could impair reef resilience. To understand fully the recovery potential of coral reefs, we must learn to listen. PMID:29712839

Mapping Mesophotic Reefs Along the Brazilian Continental Margin

NASA Astrophysics Data System (ADS)

Bastos, A.; Moura, R.; Amado Filho, G.; Ferreira, L.; Boni, G.; Vedoato, F.; D'Agostini, D.; Lavagnino, A. C.; Leite, M. D.; Quaresma, V.

2017-12-01

Submerged or drowned reefs constitute an important geological record of sea level variations, forming the substrate for the colonization of modern benthic mesophotic communities. Although mapping mesophotic reefs has increased in the last years, their spatial distribution is poorly known and the worldwide occurrence of this reef habitat maybe underestimated. The importance in recognizing the distribution of mesophotic reefs is that they can act as a refuge for corals during unsuitable environmental conditions and a repository for shallow water corals. Here we present the result of several acoustic surveys that mapped and discovered new mesophotic reefs along the Eastern and Equatorial Brazilian Continental Margin. Seabed mapping was carried out using multibeam and side scan sonars. Ground truthing was obtained using drop camera or scuba diving. Mesophotic reefs were mapped in water depths varying from 30 to 100m and under distinct oceanographic conditions, especially in terms of river load input and shelf width. Reefs showed distinct morphologies, from low relief banks and paleovalleys to shelf edge ridges. Extensive occurrence of low relief banks were mapped along the most important coralline complex province in the South Atlantic, the Abrolhos Shelf. These 30 to 40m deep banks, have no more than 3 meters in height and may represent fringing reefs formed during sea level stabilization. Paleovalleys mapped along the eastern margin showed the occurrence of coralgal ledges along the channel margins. Paleovalleys are usually deeper than 45m and are associated with outer shelf rhodolith beds. Shelf edge ridges (80 to 120m deep) were mapped along both margins and are related to red algal encrusting irregular surfaces that have more than 3m in height, forming a rigid substrate for coral growth. Along the Equatorial Margin, off the Amazon mouth, shelf edge patch reefs and rhodolith beds forming encrusting surfaces and shelf edge ridges were mapped in water depths greater than 100m. Thus, the occurrence of mesophotic reefs along the Brazilian Margin is influenced by transgressive morphological features, which could be used as a surrogate for mesophotic reef distribution. The extensive occurrence of rhodolith beds on the outer shelf characterizes most of these reefs.

The role of coral reef rugosity in dissipating wave energy and coastal protection

NASA Astrophysics Data System (ADS)

Harris, Daniel; Rovere, Alessio; Parravicini, Valeriano; Casella, Elisa

2016-04-01

Coral reefs are the most effective natural barrier in dissipating wave energy through breaking and bed friction. The attenuation of wave energy by coral reef flats is essential in the protection and stability of coral reef aligned coasts and reef islands. However, the effectiveness of wave energy dissipation by coral reefs may be diminished under future climate change scenarios with a potential reduction of coral reef rugosity due to increased stress environmental stress on corals. The physical roughness or rugosity of coral reefs is directly related to ecological diversity, reef health, and hydrodynamic roughness. However, the relationship between physical roughness and hydrodynamic roughness is not well understood despite the crucial role of bed friction in dissipating wave energy in coral reef aligned coasts. We examine the relationship between wave energy dissipation across a fringing reef in relation to the cross-reef ecological zonation and the benthic hydrodynamic roughness. Waves were measured by pressure transducers in a cross-reef transect on the reefs flats and post processed on a wave by wave basis to determine wave statistics such as significant wave height and wave period. Results from direct wave measurement were then used to calibrate a 1D wave dissipation model that incorporates dissipation functions due to bed friction and wave breaking. This model was used to assess the bed roughness required to produce the observed wave height dissipation during propagation from deep water and across the coral reef flats. Changes in wave dissipation was also examined under future scenarios of sea level rise and reduced bed roughness. Three dimensional models of the benthic reef structure were produced through structure-from-motion photogrammetry surveys. Reef rugosity was then determined from these surveys and related to the roughness results from the calibrated model. The results indicate that applying varying roughness coefficients as the benthic ecological assemblage changes produces the most accurate assessment of wave energy dissipation across the reef flat. However, the modelled results of bed roughness (e.g. 0.01 for the fore-reef slope) were different to the directly measured rugosity values (0.05 for the fore-reef slope) from three dimension structure-from-motion surveys. In spite of this, the modelled and directly measured values of roughness are similar considering the difficulties outlined in previous research when relating the coral reef structural complexity to a single value of hydrodynamic roughness. Bed roughness was shown to be a secondary factor behind wave breaking in dissipating wave energy. However, without bed friction waves could be an order of magnitude higher in the back-reef environment. Bed friction is also increasingly important in wave dissipation at higher sea levels as wave energy dissipation due to wave breaking is reduced at greater depths. This shows that maintaining a structurally diverse and healthy reef is crucial under future sea level rise scenarios in order to maintain the protection of coastal environments. These results also indicate that significant geomorphic change in coastal environments will occur due to reduced wave dissipation at higher sea levels unless reefs are capable of keeping up with forecasted sea level rise.

Southeast Georgia embayment high-resolution seismic-reflection survey

USGS Publications Warehouse

Edsall, Douglas W.

1979-01-01

A high-resolution seismic survey of the offshore part of the Southeast Georgia Embayment on about a 20 km spacing was completed in 1976. A stratigraphic analyses of the data shows that the largest controlling factor in the depositional history of the shelf has been the Gulf Stream. These currents have shifted back and forth across the shelf, at times incising into shelf sediments, and at all times blocking much of the accumulation of Cenozoic sediments seaward of the Florida-Hatteras Slope. In the southern region the Gulf Stream maintained its present position since Miocene time, blocking the accumulation of Pliocene and younger rocks on the Plateau. Northward, in the middle, region the currents turned slightly to the northeast. The inner portion of the Blake Plateau has been scoured of sediments since the Paleocene in this area, and scouring has also occurred on the shelf from time to time. In the northern part of the survey area a more easterly flow of the Gulf Stream has allowed Eocene and younger rocks to be deposited on the Plateau. Line drawings and a geologic map show the distribution of the various Cretaceous and Cenozoic units. A number of potential environmental hazards or constraints to petroleum development seen in the reflection data are identified. Besides current scour and erosion features, these include gravity faults on the slope, a slump, faulting on the inner Blake Plateau, the shelf edge reef, and deep water reefs on the Blake Plateau.

Shelf stratigraphy and the influence of antecedent substrate on Holocene reef development, south Oahu, Hawaii

USGS Publications Warehouse

Grossman, E.E.; Barnhardt, W.A.; Hart, P.; Richmond, B.M.; Field, M.E.

2006-01-01

Paired analyses of drill cores and high-resolution seismic reflection data show that development of Holocene framework reefs on the Oahu (Hawaii) shelf is limited to settings of low wave energy and to the period 8000 to 3000 yr BP. A prominent bounding surface that is mapped across much of the Oahu shelf is an erosion surface cut into Marine Isotope Stages 5 and 7 limestones that show extensive loss of primary porosity, aragonite, and MgCO3 owing to meteoric and vadose-zone diagenesis. This acoustic reflector is found exposed at the surface where wave energy is high or in the shallow subsurface below Holocene reef and sand sheet deposits where energy is low. Ship-towed video along 30 km of the shelf reveals a steady decrease in limestone accumulation from offshore of Honolulu southeast to Koko Head where the seafloor is characterized by volcanic pavement and/or thin sand deposits. This may reflect the build-up of late Pleistocene volcanics associated with the Hanauma Bay eruption (30,000-7000 yr BP) that now comprise the substrate in depths shallow enough to limit reef accretion. The absence of significant Holocene reef build-up on the south Oahu shelf is consistent with observations from north-facing coasts that lack Holocene reefs, indicating that Holocene reef formation in Hawaii is complex and patchy.

Predatory fish depletion and recovery potential on Caribbean reefs.

PubMed

Valdivia, Abel; Cox, Courtney Ellen; Bruno, John Francis

2017-03-01

The natural, prehuman abundance of most large predators is unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomass at a given location (that is, the predator carrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reef fish biomass and several anthropogenic and environmental variables at 39 reefs across the Caribbean to (i) estimate their roles determining local predator biomass and (ii) determine site-specific recovery potential if fishing was eliminated. We show that predatory reef fish biomass tends to be higher in marine reserves but is strongly negatively related to human activities, especially coastal development. However, human activities and natural factors, including reef complexity and prey abundance, explain more than 50% of the spatial variation in predator biomass. Comparing site-specific predator carrying capacities to field observations, we infer that current predatory reef fish biomass is 60 to 90% lower than the potential supportable biomass in most sites, even within most marine reserves. We also found that the scope for recovery varies among reefs by at least an order of magnitude. This suggests that we could underestimate unfished biomass at sites that provide ideal conditions for predators or greatly overestimate that of seemingly predator-depleted sites that may have never supported large predator populations because of suboptimal environmental conditions.

Micro-topography mediates interactions between corals, algae, and herbivorous fishes on coral reefs

NASA Astrophysics Data System (ADS)

Brandl, S. J.; Hoey, A. S.; Bellwood, D. R.

2014-06-01

Processes occurring during the early life stages of corals are important for the replenishment of coral assemblages and the resilience of coral reefs. However, the factors influencing early life stages of corals are not well understood, and the role of micro-topographic complexity for habitat associations of juvenile corals is largely unexplored. This study investigated the microhabitat distribution patterns of early life stages of corals and a potential macroalgal competitor ( Turbinaria ornata) across two reef zones (reef crest and outer reef flat) on Lizard Island, Great Barrier Reef. In both reef zones, both corals and T. ornata were significantly more abundant in concealed microhabitats than in semi-concealed or open microhabitats (GLMM: P < 0.001). The prevalence of juvenile corals and T. ornata within concealed environments suggests that they might be effective refuges from grazing by herbivorous fishes. The density of juvenile corals was positively related, and density of T. ornata negatively related to the abundance of two groups of herbivorous fishes, pairing rabbitfishes, and surgeonfishes in the genus Zebrasoma (BEST ENV-BIO: r s = 0.72, P < 0.01), which feed in concealed microhabitats. This correlative evidence suggests that crevices may be important for early life stages of both coral and macroalgae, and that a specific suite of crevice-feeding fishes may influence benthic community dynamics in these microhabitats.

Habitat preferences of a corallivorous reef fish: predation risk versus food quality

NASA Astrophysics Data System (ADS)

Brooker, R. M.; Munday, P. L.; Mcleod, I. M.; Jones, G. P.

2013-09-01

Many animals preferentially select a habitat from a range of those potentially available. However, the consequences of these preferences for distribution and abundance, and the underlying basis of habitat preferences are often unknown. The present study, conducted at Great Keppel Island, Australia, examined how distribution and abundance of an obligate corallivorous filefish, Oxymonacanthus longirostris, relates to coral architecture and diversity. The main drivers of the distribution and abundance of O. longirostris among reefs were coral species richness and availability of branching coral. Feeding territories had a higher percentage of Acropora coral than surrounding habitat. In addition, feeding territories had a higher percentage of the structurally important branching coral, Acropora nobilis, and a primary prey species, Acropora millepora. A series of pair-wise choice experiments in which both structural complexity and coral tissue quality were independently manipulated showed that habitat choice was primarily based on structural complexity and shelter characteristics. In addition, the choice for the preferred coral ( A. nobilis) was stronger in the presence of a piscivorous fish. These results indicate that species-diverse coral habitats, which provide sufficient structural complexity along with nutritionally important prey, are essential for population persistence of this small, corallivorous reef fish.

Unseen players shape benthic competition on coral reefs.

PubMed

Barott, Katie L; Rohwer, Forest L

2012-12-01

Recent work has shown that hydrophilic and hydrophobic organic matter (OM) from algae disrupts the function of the coral holobiont and promotes the invasion of opportunistic pathogens, leading to coral morbidity and mortality. Here we refer to these dynamics as the (3)DAM [dissolved organic matter (DOM), direct contact, disease, algae and microbes] model. There is considerable complexity in coral-algae interactions; turf algae and macroalgae promote heterotrophic microbial overgrowth of coral, macroalgae also directly harm the corals via hydrophobic OM, whereas crustose coralline algae generally encourage benign microbial communities. In addition, complex flow patterns transport OM and pathogens from algae to downstream corals, and direct algal contact enhances their delivery. These invisible players (microbes, viruses, and OM) are important drivers of coral reefs because they have non-linear responses to disturbances and are the first to change in response to perturbations, providing near real-time trajectories for a coral reef, a vital metric for conservation and restoration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Early Miocene shortening in the lower Comondú Group in Baja California Sur (México)

NASA Astrophysics Data System (ADS)

Bonini, Marco; Cerca, Mariano; Moratti, Giovanna; López-Martínez, Margarita; Corti, Giacomo; Gracia-Marroquín, Diego

2017-11-01

The Late Oligocene-Early Miocene volcaniclastic deposits of Baja California Sur form most of the exposed western margin of the Gulf of California rift. In some places these deposits, collectively referred to as Comondú Group, show complex deformation patterns given by the coexistence of tectonic and gravitational features. The area north of La Paz is characterized by the occurrence of several slump bodies, which are displaced by normal faults connected with the rift opening. In some places we have identified 100's m scale thrust-related folds and reverse faults that we have interpreted as shortening features. The latter displace the slump layers and are offset by the normal faults. If confirmed, this would represent the first report of a shortening event in the Early Miocene volcaniclastic deposits of Baja California Sur. The observed shortening has modest magnitude (ca 3-5% bulk shortening), and has been detected in a sector extending over 100 km north from La Paz. New 40Ar-39*Ar ages, integrated with existing radiometric age datasets, constrain the timing of this shortening episode. The rocks affected by shortening have ages between 24 and 21 Ma, and are capped by undeformed volcanic rocks with ages spanning between 19.4 and 17.2 Ma. These relationships define an intra-Early Miocene unconformity, which we interpret to be related to the shortening deformation. The available timing constraints allow us to infer that a main ENE-to-ESE-trending shortening was short-lived, possibly ca. 19.4-21 Ma. The account of this shortening event may shed some light on the complex subduction and microplate processes that preceded the continental rifting of the Gulf of California.

Pleistocene corals of the Florida keys: Architects of imposing reefs - Why?

USGS Publications Warehouse

Lidz, B.H.

2006-01-01

Five asymmetrical, discontinuous, stratigraphically successive Pleistocene reef tracts rim the windward platform margin off the Florida Keys. Built of large head corals, the reefs are imposing in relief (???30 m high by 1 km wide), as measured from seismic profiles. Well dated to marine oxygen isotope substages 5c, 5b, and 5a, corals at depth are inferred to date to the Stage 6/5 transition. The size of these reefs attests to late Pleistocene conditions that repeatedly induced vigorous and sustained coral growth. In contrast, the setting today, linked to Florida Bay and the Gulf of Mexico, is generally deemed marginal for reef accretion. Incursion onto the reef tract of waters that contain seasonally inconsistent temperature, salinity, turbidity, and nutrient content impedes coral growth. Fluctuating sea level and consequent settings controlled deposition. The primary dynamic was position of eustatic zeniths relative to regional topographic elevations. Sea level during the past 150 ka reached a maximum of ???10.6 m higher than at present ???125 ka, which gave rise to an inland coral reef (Key Largo Limestone) and ooid complex (Miami Limestone) during isotope substage 5e. These formations now form the Florida Keys and a bedrock ridge beneath The Quicksands (Gulf of Mexico). High-precision radiometric ages and depths of dated corals indicate subsequent apices remained ???15 to 9 m, respectively, below present sea level. Those peaks provided accommodation space sufficient for vertical reef growth yet exposed a broad landmass landward of the reefs for >100 ka. With time, space, lack of bay waters, and protection from the Gulf of Mexico, corals thrived in clear oceanic waters of the Gulf Stream, the only waters to reach them.

Snapping shrimp sound production patterns on Caribbean coral reefs: relationships with celestial cycles and environmental variables

NASA Astrophysics Data System (ADS)

Lillis, Ashlee; Mooney, T. Aran

2018-06-01

The rich acoustic environment of coral reefs, including the sounds of a variety of fish and invertebrates, is a reflection of the structural complexity and biological diversity of these habitats. Emerging interest in applying passive acoustic monitoring and soundscape analysis to measure coral reef habitat characteristics and track ecological patterns is hindered by a poor understanding of the most common and abundant sound producers on reefs—the snapping shrimp. Here, we sought to address several basic biophysical drivers of reef sound by investigating acoustic activity patterns of snapping shrimp populations on two adjacent coral reefs using a detailed snap detection analysis routine to a high-resolution 2.5-month acoustic dataset from the US Virgin Islands. The reefs exhibited strong diel and lunar periodicity in snap rates and clear spatial differences in snapping levels. Snap rates peaked at dawn and dusk and were higher overall during daytime versus nighttime, a seldom-reported pattern in earlier descriptions of diel snapping shrimp acoustic activity. Small differences between the sites in snap rate rhythms were detected and illustrate how analyses of specific soundscape elements might reveal subtle between-reef variation. Snap rates were highly correlated with environmental variables, including water temperature and light, and were found to be sensitive to changes in oceanographic forcing. This study further establishes snapping shrimp as key players in the coral reef chorus and provides evidence that their acoustic output reflects a combination of environmental conditions, celestial influences, and spatial habitat variation. Effective application of passive acoustic monitoring in coral reef habitats using snap rates or snapping-influenced acoustic metrics will require a mechanistic understanding of the underlying spatial and temporal variation in snapping shrimp sound production across multiple scales.

The coral reefs optimization algorithm: a novel metaheuristic for efficiently solving optimization problems.

PubMed

Salcedo-Sanz, S; Del Ser, J; Landa-Torres, I; Gil-López, S; Portilla-Figueras, J A

2014-01-01

This paper presents a novel bioinspired algorithm to tackle complex optimization problems: the coral reefs optimization (CRO) algorithm. The CRO algorithm artificially simulates a coral reef, where different corals (namely, solutions to the optimization problem considered) grow and reproduce in coral colonies, fighting by choking out other corals for space in the reef. This fight for space, along with the specific characteristics of the corals' reproduction, produces a robust metaheuristic algorithm shown to be powerful for solving hard optimization problems. In this research the CRO algorithm is tested in several continuous and discrete benchmark problems, as well as in practical application scenarios (i.e., optimum mobile network deployment and off-shore wind farm design). The obtained results confirm the excellent performance of the proposed algorithm and open line of research for further application of the algorithm to real-world problems.

Discovery of a living coral reef in the coastal waters of Iraq

PubMed Central

Pohl, Thomas; Al-Muqdadi, Sameh W.; Ali, Malik H.; Fawzi, Nadia Al-Mudaffar; Ehrlich, Hermann; Merkel, Broder

2014-01-01

Until now, it has been well-established that coral complex in the Arabian/Persian Gulf only exist in the coastal regions of Bahrain, Iran, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates and it was thought that there are no coral reefs in Iraq. However, here for the first time we show the existence of a living 28 km2 large coral reef in this country. These corals are adapted to one of the most extreme coral-bearing environments on earth: the seawater temperature in this area ranges between 14 and 34°C. The discovery of the unique coral reef oasis in the turbid coastal waters of Iraq will stimulate the interest of governmental agencies, environmental organizations, as well as of the international scientific community working on the fundamental understanding of coral marine ecosystems and global climate today. PMID:24603901

Discovery of a living coral reef in the coastal waters of Iraq.

PubMed

Pohl, Thomas; Al-Muqdadi, Sameh W; Ali, Malik H; Fawzi, Nadia Al-Mudaffar; Ehrlich, Hermann; Merkel, Broder

2014-03-06

Until now, it has been well-established that coral complex in the Arabian/Persian Gulf only exist in the coastal regions of Bahrain, Iran, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates and it was thought that there are no coral reefs in Iraq. However, here for the first time we show the existence of a living 28 km(2) large coral reef in this country. These corals are adapted to one of the most extreme coral-bearing environments on earth: the seawater temperature in this area ranges between 14 and 34°C. The discovery of the unique coral reef oasis in the turbid coastal waters of Iraq will stimulate the interest of governmental agencies, environmental organizations, as well as of the international scientific community working on the fundamental understanding of coral marine ecosystems and global climate today.

The Coral Reefs Optimization Algorithm: A Novel Metaheuristic for Efficiently Solving Optimization Problems

PubMed Central

Salcedo-Sanz, S.; Del Ser, J.; Landa-Torres, I.; Gil-López, S.; Portilla-Figueras, J. A.

2014-01-01

This paper presents a novel bioinspired algorithm to tackle complex optimization problems: the coral reefs optimization (CRO) algorithm. The CRO algorithm artificially simulates a coral reef, where different corals (namely, solutions to the optimization problem considered) grow and reproduce in coral colonies, fighting by choking out other corals for space in the reef. This fight for space, along with the specific characteristics of the corals' reproduction, produces a robust metaheuristic algorithm shown to be powerful for solving hard optimization problems. In this research the CRO algorithm is tested in several continuous and discrete benchmark problems, as well as in practical application scenarios (i.e., optimum mobile network deployment and off-shore wind farm design). The obtained results confirm the excellent performance of the proposed algorithm and open line of research for further application of the algorithm to real-world problems. PMID:25147860

Ability to home in small site-attached coral reef fishes.

PubMed

Booth, D J

2016-08-01

The ability of two common, site-attached coral-reef fishes to return to their home corals after displacement was investigated in a series of field experiments at One Tree Island, southern Great Barrier Reef. The humbug Dascyllus aruanus was displaced up to 250 m, with 42% of individuals returning home, irrespective of body size, displacement, direction (up or across currents) and route complexity, while for the lemon damselfish Pomacentrus moluccensis 35% of individuals returned overall, with 33% from the greatest displacement, 100 m along a reef edge. Given that the home range of both species is <1 m(2) , over their 10+ year life span, the mechanisms and motivations for such homing ability are unclear but it may allow resilience if fishes are displaced by storm events, allowing rapid return to home corals. © 2016 The Fisheries Society of the British Isles.

Miocene diagenetic and epigenetic strontium mineralization in calcareous series from Cyprus and the Arabian Gulf: Metallogenic perspective on sub- and suprasalt redox-controlled base metal deposits

NASA Astrophysics Data System (ADS)

Dill, Harald G.; Henjes-Kunst, Friedhelm; Berner, Zsolt; Stüben, Doris

2009-04-01

During the Neogene, celestite deposits evolved in the Neo-Tethys basins, in what is today called the Mediterranean Sea and the Arabian Gulf. Two evaporite deposits, in Cyprus and in Qatar have been investigated from the sedimentological and mineralogical point of view with emphasis placed on Sr, S and Ca isotopes of carbonate, gypsum and celestite. During the early Miocene shallow marine environments occurred in the Gulf region and in Cyprus both of which are abundant in syndiagenetic sulphate minerals. The calcareous environments had a strong impact on the fluid migration leading to the Sr mineralization. In the Gulf region algal biostromes favored the lateral migration of fluids but had a sealing effect so that any epigenetic mineralization based on vertical fluid flow was hampered. In contrast, the Cypriot depocentre overlying the Troodos ophiolite is dominated by patch and knoll reefs (bioherms) which provide enough porosity and permeability to be favorable for the circulation of fluids with a strong vertical component. Owing to these changes in the calcareous host series, epigenetic sulphate mineralization evolved in Cyprus during the late Miocene. This occurred as the Mediterranean Sea gradually became isolated from the open ocean and, as a precursor to the "Messinian salinity crisis" evaporitic brines circulated deep into the Meso-Cenozoic platform sediments and the underlying Troodos ophiolite where these fluids leached some base metals and sulphur for the celestite mineralization. The Red Sea Rifting was at full swing during the Late Miocene and its northern propagation into the Mediterranean Sea is assumed to have had a structural control on the positioning of the Sr deposits in Cyprus. In the Gulf area, the final closure of the Neo-Tethys and Zagros folding terminated deposition of marine calcareous rocks and alluvial-fluvial siliciclastic rocks were deposited across an unconformity. Missing circulation of highly saline brines was responsible for the absence of an epigenetic Sr mineralization of Cyprus-type in the Gulf area. Assemblages of light (e.g. zeolites) and heavy minerals (e.g. rutile, zoisite, clinopyroxene) and Ca isotope analyses support basic igneous rocks as the source for the detrital and dissolved matter in the depositional environments in Cyprus and the Arabian Gulf. The Ca isotope data imply formation of the sulphate and carbonate minerals in a marine environment without significant contributions of more radiogenic 40Ca coming from old continental crust, e.g., the Kyrenia Range or Mamonia Complex, both of which containing rocks as old as Permian. Cyprus-type (bioherm-type) and Gulf-type (biostrome-type) evaporites are potential progenitors of sediment-hosted mineral deposits (SHSCD) or base metal vein-type deposits. Syndiagenetic celestite-bearing evaporites of the Gulf-type are a model source and progenitor of base metal deposits of stratigraphically-controlled fixed or mobile reductants such as Kupferschiefer-type deposits. Is the Arabian Gulf a Kupferschiefer basin in the making? The epigenetic celestite-bearing mineralization of the Cyprus-type reflects an advanced stage of fluid migration relative to the celestite deposits along the Trucial coast but this brine mobilization failed to create a base metal deposit of its own mainly due to the absence of fixed or mobile reductants. These reductants were present in the western Mediterranean regions in Tunisia and Algeria, where evaporite-associated base metal deposits are going to be mined and in the Mesozoic through Cenozoic platform sediments in central Europe, where numerous suprasalt unconformity-related metal deposits were mined in the past.

Characterization of measurement errors using structure-from-motion and photogrammetry to measure marine habitat structural complexity.

PubMed

Bryson, Mitch; Ferrari, Renata; Figueira, Will; Pizarro, Oscar; Madin, Josh; Williams, Stefan; Byrne, Maria

2017-08-01

Habitat structural complexity is one of the most important factors in determining the makeup of biological communities. Recent advances in structure-from-motion and photogrammetry have resulted in a proliferation of 3D digital representations of habitats from which structural complexity can be measured. Little attention has been paid to quantifying the measurement errors associated with these techniques, including the variability of results under different surveying and environmental conditions. Such errors have the potential to confound studies that compare habitat complexity over space and time. This study evaluated the accuracy, precision, and bias in measurements of marine habitat structural complexity derived from structure-from-motion and photogrammetric measurements using repeated surveys of artificial reefs (with known structure) as well as natural coral reefs. We quantified measurement errors as a function of survey image coverage, actual surface rugosity, and the morphological community composition of the habitat-forming organisms (reef corals). Our results indicated that measurements could be biased by up to 7.5% of the total observed ranges of structural complexity based on the environmental conditions present during any particular survey. Positive relationships were found between measurement errors and actual complexity, and the strength of these relationships was increased when coral morphology and abundance were also used as predictors. The numerous advantages of structure-from-motion and photogrammetry techniques for quantifying and investigating marine habitats will mean that they are likely to replace traditional measurement techniques (e.g., chain-and-tape). To this end, our results have important implications for data collection and the interpretation of measurements when examining changes in habitat complexity using structure-from-motion and photogrammetry.

Florida Integrated Science Center (FISC) Coral Reef Research

USGS Publications Warehouse

Poore, D.Z.

2008-01-01

Coral reefs provide important ecosystem services such as shoreline protection and the support of lucrative industries including fisheries and tourism. Such ecosystem services are being compromised as reefs decline due to coral disease, climate change, overfishing, and pollution. There is a need for focused, integrated science to understand the complex ecological interactions and effects of these many stressors and to provide information that will effectively guide policies and best management practices to preserve and restore these important resources. The U.S. Geological Survey Florida Integrated Science Center (USGS-FISC) is conducting a coordinated Coral Reef Research Project beginning in 2009. Specific research topics are aimed at addressing priorities identified in the 'Strategic Science for Coral Ecosystems 2007-2011' document (U.S. Geological Survey, 2007). Planned research will include a blend of historical, monitoring, and process studies aimed at improving our understanding of the development, current status and function, and likely future changes in coral ecosystems. Topics such as habitat characterization and distribution, coral disease, and trends in biogenic calcification are major themes of understanding reef structure, ecological integrity, and responses to global change.

Life on the edge: corals in mangroves and climate change

USGS Publications Warehouse

Rogers, Caroline S.; Herlan, James J.

2012-01-01

Coral diseases have played a major role in the degradation of coral reefs in the Caribbean, including those in the US Virgin Islands (USVI). In 2005, bleaching affected reefs throughout the Caribbean, and was especially severe on USVI reefs. Some corals began to regain their color as water temperatures cooled, but an outbreak of disease (primarily white plague) led to losses of over 60% of the total live coral cover. Montastraea annularis, the most abundant coral, was disproportionately affected, and decreased in relative abundance. The threatened species Acropora palmata bleached for the first time on record in the USVI but suffered less bleaching and less mortality from disease than M. annularis. Acropora palmata and M. annularis are the two most significant species in the USVI because of their structural role in the architecture of the reefs, the large size of their colonies, and their complex morphology. The future of the USVI reefs depends largely on their fate. Acropora palmata is more likely to recover than M. annularis for many reasons, including its faster growth rate, and its lower vulnerability to bleaching and disease.

ACHP | News

Science.gov Websites

reefs in North America, supporting complex ecosystems of marine life that have thrived generation after Key West at the Dr. Nancy Foster Environmental Complex in Key West. Credit: Craig Wanous, Florida Keys Environmental Complex in Key West. Credit: Craig Wanous, Florida Keys National Marine Sanctuary. The National

Hydrodynamics of a bathymetrically complex fringing coral reef embayment: Wave climate, in situ observations, and wave prediction

USGS Publications Warehouse

Hoeke, R.; Storlazzi, C.; Ridd, P.

2011-01-01

This paper examines the relationship between offshore wave climate and nearshore waves and currents at Hanalei Bay, Hawaii, an exposed bay fringed with coral reefs. Analysis of both offshore in situ data and numerical hindcasts identify the predominance of two wave conditions: a mode associated with local trade winds and an episodic pattern associated with distant source long-period swells. Analysis of 10 months of in situ data within the bay show that current velocities are up to an order of magnitude greater during long-period swell episodes than during trade wind conditions; overall circulation patterns are also fundamentally different. The current velocities are highly correlated with incident wave heights during the swell episodes, while they are not during the modal trade wind conditions. A phase-averaged wave model was implemented with the dual purpose of evaluating application to bathymetrically complex fringing reefs and to examine the propagation of waves into the nearshore in an effort to better explain the large difference in observed circulation during the two offshore wave conditions. The prediction quality of this model was poorer for the episodic condition than for the lower-energy mode, however, it illustrated how longer-period swells are preferentially refracted into the bay and make available far more nearshore wave energy to drive currents compared to waves during modal conditions. The highly episodic circulation, the nature of which is dependent on complex refraction patterns of episodic, long-period swell has implications for flushing and sediment dynamics for incised fringing reef-lined bays that characterize many high islands at low latitudes around the world.

The importance of sponges and mangroves in supporting fish communities on degraded coral reefs in Caribbean Panama.

PubMed

Seemann, Janina; Yingst, Alexandra; Stuart-Smith, Rick D; Edgar, Graham J; Altieri, Andrew H

2018-01-01

Fish communities associated with coral reefs worldwide are threatened by habitat degradation and overexploitation. We assessed coral reefs, mangrove fringes, and seagrass meadows on the Caribbean coast of Panama to explore the influences of their proximity to one another, habitat cover, and environmental characteristics in sustaining biomass, species richness and trophic structure of fish communities in a degraded tropical ecosystem. We found 94% of all fish across all habitat types were of small body size (≤10 cm), with communities dominated by fishes that usually live in habitats of low complexity, such as Pomacentridae (damselfishes) and Gobiidae (gobies). Total fish biomass was very low, with the trend of small fishes from low trophic levels over-represented, and top predators under-represented, relative to coral reefs elsewhere in the Caribbean. For example, herbivorous fishes comprised 27% of total fish biomass in Panama relative to 10% in the wider Caribbean, and the small parrotfish Scarus iseri comprised 72% of the parrotfish biomass. We found evidence that non-coral biogenic habitats support reef-associated fish communities. In particular, the abundance of sponges on a given reef and proximity of mangroves were found to be important positive correlates of reef fish species richness, biomass, abundance and trophic structure. Our study indicates that a diverse fish community can persist on degraded coral reefs, and that the availability and arrangement within the seascape of other habitat-forming organisms, including sponges and mangroves, is critical to the maintenance of functional processes in such ecosystems.

Coralline reefs classification in Banco Chinchorro, Mexico

NASA Astrophysics Data System (ADS)

Contreras-Silva, Ameris I.; López-Caloca, Alejandra A.

2009-09-01

The coralline reefs in Banco Chinchorro, Mexico, are part of the great reef belt of the western Atlantic. This reef complex is formed by an extensive coralline structure with great biological richness and diversity of species. These colonies are considered highly valuable ecologically, economically, socially and culturally, and they also inherently provide biological services. Fishing and scuba diving have been the main economic activities in this area for decades. However, in recent years, there has been a bleaching process and a decrease of the coral colonies in Quintana Roo, Mexico. This drop is caused mainly by the production activities performed in the oil platforms and the presence of hurricanes among other climatic events. The deterioration of the reef system can be analyzed synoptically using remote sensing. Thanks to this type of analysis, it is possible to have updated information of the reef conditions. In this paper, satellite imagery in Landsat TM and SPOT 5 is applied in the coralline reefs classification in the 1980- 2006 time period. Thus, an integral analysis of the optical components of the water surrounding the coralline reefs, such as on phytoplankton, sediments, yellow substance and even on the same water adjacent to the coral colonies, is performed. The use of a texture algorithm (Markov Random Field) was a key tool for their identification. This algorithm, does not limit itself to image segmentation, but also works on edge detection. In future work the multitemporal analysis of the results will determine the deterioration degree of these habitats and the conservation status of the coralline areas.

Monitoring the impacts of Ocean Acidification on coral reef bioerosion: challenges, methods, recommendations

NASA Astrophysics Data System (ADS)

Enochs, I.; Manzello, D.; Carlton, R.

2013-05-01

Coral reef habitats exist as a dynamic balance between the additive process of calcification and the destructive effects of erosion. A disruption to either the positive or negative side of the coral reef carbonate budget can push a reef system towards rapid collapse. It is well understood that Ocean Acidification (OA) may impair calcification and emerging experimental evidence suggests that it will likely increase the erosive potential of a diverse suite of bioeroding taxa. This may lead to previously unforeseen scenarios where reef framework degradation occurs at a faster pace than that predicted by more simplistic models, resulting from the multifaceted impacts of both slower coral growth and enhanced rates of habitat erosion. As such, it is of paramount importance that monitoring plans tasked with assessing reef resilience to climate change and OA incorporate methods for quantifying bioerosion. This is a complex undertaking as reef ecosystem bioerosion is the result of numerous behaviors, employed by diverse flora and fauna, operating at vastly different scales. Furthermore, these erosive processes are highly variable, dependent on seasonal fluctuations and differing between reef regions, species, individuals, and even the physical characteristics of the substrates acted upon. The strengths and weaknesses of existing bioerosion monitoring methodologies are discussed, ranging from quantification of single species erosion rates to multi-phyletic census-based approaches. Traditional techniques involving the weight change of carbonate blocks are compared alongside more modern methodologies such as micro computed tomography. Finally, recommendations are made for a comprehensive monitoring strategy, incorporating multiple methodologies in a time and cost-effective manner.

Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean

PubMed Central

Pina-Amargós, Fabián; González-Sansón, Gaspar; Martín-Blanco, Félix

2014-01-01

Marine reserves can restore fish abundance and diversity in areas impacted by overfishing, but the effectiveness of reserves in developing countries where resources for enforcement are limited, have seldom been evaluated. Here we assess whether the establishment in 1996 of the largest marine reserve in the Caribbean, Gardens of the Queen in Cuba, has had a positive effect on the abundance of commercially valuable reef fish species in relation to neighboring unprotected areas. We surveyed 25 sites, including two reef habitats (reef crest and reef slope), inside and outside the marine reserve, on five different months, and over a one-and-a-half year period. Densities of the ten most frequent, highly targeted, and relatively large fish species showed a significant variability across the archipelago for both reef habitats that depended on the month of survey. These ten species showed a tendency towards higher abundance inside the reserve in both reef habitats for most months during the study. Average fish densities pooled by protection level, however, showed that five out of these ten species were at least two-fold significantly higher inside than outside the reserve at one or both reef habitats. Supporting evidence from previously published studies in the area indicates that habitat complexity and major benthic communities were similar inside and outside the reserve, while fishing pressure appeared to be homogeneous across the archipelago before reserve establishment. Although poaching may occur within the reserve, especially at the boundaries, effective protection from fishing was the most plausible explanation for the patterns observed. PMID:24688853

Holocene reef development where wave energy reduces accommodation

USGS Publications Warehouse

Grossman, Eric E.; Fletcher, Charles H.

2004-01-01

Analyses of 32 drill cores obtained from the windward reef of Kailua Bay, Oahu, Hawaii, indicate that high wave energy significantly reduced accommodation space for reef development in the Holocene and produced variable architecture because of the combined influence of sea-level history and wave exposure over a complex antecedent topography. A paleostream valley within the late Pleistocene insular limestone shelf provided accommodation space for more than 11 m of vertical accretion since sea level flooded the bay 8000 yr BP. Virtually no net accretion (pile-up of fore-reef-derived rubble (rudstone) and sparse bindstone, and (3) a final stage of catch-up bindstone accretion in depths > 6 m. Coral framestone accreted at rates of 2.5-6.0 mm/yr in water depths > 11 m during the early Holocene; it abruptly terminated at ~4500 yr BP because of wave scour as sea level stabilized. More than 4 m of rudstone derived from the upper fore reef accreted at depths of 6 to 13 m below sea level between 4000 and 1500 yr BP coincident with late Holocene relative sea-level fall. Variations in the thickness, composition, and age of these reef facies across spatial scales of 10-1000 m within Kailua Bay illustrate the importance of antecedent topography and wave-related stress in reducing accommodation space for reef development set by sea level. Although accommodation space of 6 to 17 m has existed through most of the Holocene, the Kailua reef has been unable to catch up to sea level because of persistent high wave stress.

The importance of sponges and mangroves in supporting fish communities on degraded coral reefs in Caribbean Panama

PubMed Central

Yingst, Alexandra; Stuart-Smith, Rick D.; Edgar, Graham J.; Altieri, Andrew H.

2018-01-01

Fish communities associated with coral reefs worldwide are threatened by habitat degradation and overexploitation. We assessed coral reefs, mangrove fringes, and seagrass meadows on the Caribbean coast of Panama to explore the influences of their proximity to one another, habitat cover, and environmental characteristics in sustaining biomass, species richness and trophic structure of fish communities in a degraded tropical ecosystem. We found 94% of all fish across all habitat types were of small body size (≤10 cm), with communities dominated by fishes that usually live in habitats of low complexity, such as Pomacentridae (damselfishes) and Gobiidae (gobies). Total fish biomass was very low, with the trend of small fishes from low trophic levels over-represented, and top predators under-represented, relative to coral reefs elsewhere in the Caribbean. For example, herbivorous fishes comprised 27% of total fish biomass in Panama relative to 10% in the wider Caribbean, and the small parrotfish Scarus iseri comprised 72% of the parrotfish biomass. We found evidence that non-coral biogenic habitats support reef-associated fish communities. In particular, the abundance of sponges on a given reef and proximity of mangroves were found to be important positive correlates of reef fish species richness, biomass, abundance and trophic structure. Our study indicates that a diverse fish community can persist on degraded coral reefs, and that the availability and arrangement within the seascape of other habitat-forming organisms, including sponges and mangroves, is critical to the maintenance of functional processes in such ecosystems. PMID:29610704

Novel reef fabrics from the Devonian Canning Basin, Western Australia

NASA Astrophysics Data System (ADS)

Wood, Rachel

1998-11-01

Large cement-filled cavities (0.2 to 1.5 m wide) are well developed in slope-margin sediments of the spectacular Upper Devonian (Frasnian) reefs of the Canning Basin, Western Australia, where they account for up to 50% of the primary porosity. These are here interpreted as primary reef framework cavities that formed beneath a variety of domal, tabular or laminar stromatoporoid sponges. Of particular note are those created by unusual, very thin (2 to 8 mm), laminar stromatoporoids (mainly Stachyodes australe), that formed arching, hollow domes up to 0.3 m in height and 1.5 m in diameter over the sediment surface to enclose flat-based cavities. The free undersurface of these stromatoporoids often supported a hitherto unrecognised cryptic community, dominated by pendent growth of the putative calcified cyanobacterium Renalcis, with rare intergrown lithistid sponges and spiny atrypid brachiopods. The uneven growth surface of the cryptos imparts an irregular, stromatactis-like texture to the upper surface of the remaining cavity, which is filled by early marine, finely banded, fibrous cements (mainly radiaxial calcite) interbedded with often multiple generations of geopetal sediment containing peloids and ostracod debris. This ecology yields the tabular stromatoporoid- Renalcis fabric described ubiquitously from the Canning Basin reef complex. Such unusual reef fabrics are a consequence of the ecology of shallow marine mid-Palaeozoic reefs which were quite unlike that of modern coral reefs. The frequent preservation of relatively delicate, in situ communities was due to (1) rapid and pervasive early cementation, (2) growth under non-energetic conditions, and (3) the relative insignificance of bioeroders associated with reefs at this time.

Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean.

PubMed

Pina-Amargós, Fabián; González-Sansón, Gaspar; Martín-Blanco, Félix; Valdivia, Abel

2014-01-01

Marine reserves can restore fish abundance and diversity in areas impacted by overfishing, but the effectiveness of reserves in developing countries where resources for enforcement are limited, have seldom been evaluated. Here we assess whether the establishment in 1996 of the largest marine reserve in the Caribbean, Gardens of the Queen in Cuba, has had a positive effect on the abundance of commercially valuable reef fish species in relation to neighboring unprotected areas. We surveyed 25 sites, including two reef habitats (reef crest and reef slope), inside and outside the marine reserve, on five different months, and over a one-and-a-half year period. Densities of the ten most frequent, highly targeted, and relatively large fish species showed a significant variability across the archipelago for both reef habitats that depended on the month of survey. These ten species showed a tendency towards higher abundance inside the reserve in both reef habitats for most months during the study. Average fish densities pooled by protection level, however, showed that five out of these ten species were at least two-fold significantly higher inside than outside the reserve at one or both reef habitats. Supporting evidence from previously published studies in the area indicates that habitat complexity and major benthic communities were similar inside and outside the reserve, while fishing pressure appeared to be homogeneous across the archipelago before reserve establishment. Although poaching may occur within the reserve, especially at the boundaries, effective protection from fishing was the most plausible explanation for the patterns observed.

Habitat degradation negatively affects auditory settlement behavior of coral reef fishes.

PubMed

Gordon, Timothy A C; Harding, Harry R; Wong, Kathryn E; Merchant, Nathan D; Meekan, Mark G; McCormick, Mark I; Radford, Andrew N; Simpson, Stephen D

2018-05-15

Coral reefs are increasingly degraded by climate-induced bleaching and storm damage. Reef recovery relies on recruitment of young fishes for the replenishment of functionally important taxa. Acoustic cues guide the orientation, habitat selection, and settlement of many fishes, but these processes may be impaired if degradation alters reef soundscapes. Here, we report spatiotemporally matched evidence of soundscapes altered by degradation from recordings taken before and after recent severe damage on Australia's Great Barrier Reef. Postdegradation soundscapes were an average of 15 dB re 1 µPa quieter and had significantly reduced acoustic complexity, richness, and rates of invertebrate snaps compared with their predegradation equivalents. We then used these matched recordings in complementary light-trap and patch-reef experiments to assess responses of wild fish larvae under natural conditions. We show that postdegradation soundscapes were 8% less attractive to presettlement larvae and resulted in 40% less settlement of juvenile fishes than predegradation soundscapes; postdegradation soundscapes were no more attractive than open-ocean sound. However, our experimental design does not allow an estimate of how much attraction and settlement to isolated postdegradation soundscapes might change compared with isolated predegradation soundscapes. Reductions in attraction and settlement were qualitatively similar across and within all trophic guilds and taxonomic groups analyzed. These patterns may lead to declines in fish populations, exacerbating degradation. Acoustic changes might therefore trigger a feedback loop that could impair reef resilience. To understand fully the recovery potential of coral reefs, we must learn to listen. Copyright © 2018 the Author(s). Published by PNAS.

Implications of coral harvest and transplantation on reefs in northwestern Dominica.

PubMed

Bruckner, Andrew W; Borneman, Eric H

2010-10-01

In June, 2002, the government of Dominica requested assistance in evaluating the coral culture and transplantation activities being undertaken by Oceanographic Institute of Dominica (OID), a coral farm culturing both western Atlantic and Indo-Pacific corals for restoration and commercial sales. We assessed the culture facilities of OID, the condition of reefs, potential impacts of coral collection and benefits of coral transplantation. Coral reefs (9 reefs, 3-20 m depth) were characterized by 35 species of scleractinian corals and a live coral cover of 8-35%. Early colonizing, brooders such as Porites astreoides (14.8% of all corals), P. porites (14.8%), Meandrina meandrites (14.7%) and Agaricia agaricites (9.1%) were the most abundant corals, but colonies were mostly small (mean = 25 cm diameter). Montastraea annularis (complex) was the other dominant taxa (20.8% of all corals) and colonies were larger (mean = 70 cm). Corals (pooled species) were missing an average of 20% of their tissue, with a mean of 1.4% recent mortality. Coral diseases affected 6.4% of all colonies, with the highest prevalence at Cabrits West (11.0%), Douglas Bay (12.2%) and Coconut Outer reef (20.7%). White plague and yellow band disease were causing the greatest loss of tissue, especially among M. annularis (complex), with localized impacts from corallivores, overgrowth by macroalgae, storm damage and sedimentation. While the reefs appeared to be undergoing substantial decline, restoration efforts by OlD were unlikely to promote recovery. No Pacific species were identified at OID restoration sites, yet species chosen for transplantation with highest survival included short-lived brooders (Agaricia and Porites) that were abundant in restoration sites, as well as non-reef builders (Palythoa and Erythropodium) that monopolize substrates and overgrow corals. The species of highest value for restoration (massive broadcast spawners) showed low survivorship and unrestored populations of these species were most affected by biotic stressors and human impacts, all of which need to be addressed to enhance survival of outplants. Problems with culture practices at OID, such as high water temperature, adequate light levels and persistent overgrowth by macroalgae could be addressed through simple modifications. Nevertheless, coral disease and other stressors are of major concern to the most important reef builders, as these species are less amenable to restoration, collection could threaten their survival and losses require decades to centuries to replace.

A Middle Miocene (13.5-12 Ma) deformational event constrained by volcanism along the Puna-Eastern Cordillera border, NW Argentina

NASA Astrophysics Data System (ADS)

Aramayo, Alejandro; Guzmán, Silvina; Hongn, Fernando; del Papa, Cecilia; Montero-López, Carolina; Sudo, Masafumi

2017-04-01

The features of Middle Miocene deposits in the Puna-Eastern Cordillera transition (Valles Calchaquíes) indicate that Cenozoic deformation, sedimentation and volcanism follow a complex spatiotemporal relationship. The intense volcanic activity recorded in the eastern Puna border between 14 and 11.5 Ma coincides with the occurrence of one of the most important deformation events of the Neogene tectonic evolution in the region. Studies performed across the Puna-Eastern Cordillera transition show different relationships between volcanic deposits of ca. 13.5-12.1 Ma and the Oligocene-Miocene Angastaco Formation. In this paper we describe the ash-flow tuff deposits which are the first of this type found concordant in the sedimentary fill of Valles Calchaquíes. Several analyses performed on these pyroclastic deposits allow a correlation to be made with the Alto de Las Lagunas Ignimbrite (ca. 13.5 Ma) of the Pucarilla-Cerro Tipillas Volcanic Complex located in the Puna. Outcrops of the ca. 13.5 Ma pyroclastic deposits are recognised within the Puna and the Valle Calchaquí. However, in the southern prolongation of the Valle de Hualfín (Tiopampa-Pucarilla depression) that separates the Puna from the Valle Calchaquí at these latitudes, these deposits are partially eroded and buried, and thus their occurrence is recorded only by abundant volcanic clasts included in conglomerates of the Angastaco Formation. The sedimentation of the Angastaco Formation was aborted at ca. 12 Ma in the Tiopampa-Pucarilla depression by the Pucarilla Ignimbrite, which unconformably covers the synorogenic units. On the contrary, in the Valle Calchaquí the sedimentation of the Angastaco Formation continued until the Late Miocene. The different relationships between the Miocene Angastaco Formation and the ignimbrites with ages of ca. 13.5 and ca. 12 Ma reveal that in this short period ( 1.5 m.y.) a significant deformation event took place and resulted in marked palaeogeographic changes, as evidenced by stratigraphic-sedimentological and chronological records in the Angastaco Formation.

Geologic map of the Topock 7.5’ quadrangle, Arizona and California

USGS Publications Warehouse

Howard, Keith A.; John, Barbara E.; Nielson, Jane E.; Miller, Julia M.G.; Wooden, Joseph L.

2013-01-01

The Topock quadrangle exposes a structurally complex part of the Colorado River extensional corridor and also exposes deposits that record landscape evolution during the history of the Colorado River. Paleoproterozoic gneisses and Mesoproterozoic granitoids and intrusive sheets are exposed through tilted cross-sectional thicknesses of many kilometers. Intruding them are a series of Mesozoic to Tertiary igneous rocks including dismembered parts of the Late Cretaceous Chemehuevi Mountains Plutonic Suite. Plutons of this suite in Arizona, if structurally restored for Miocene extension, formed cupolas capping the Chemehuevi Mountains batholith in California. Thick (1–3 km) Miocene sections of volcanic rocks, sedimentary breccias, conglomerate, and sandstone rest nonconformably on the Proterozoic rocks and record the structural and depositional evolution of the Colorado River extensional corridor. Four major Miocene low-angle normal faults and a steep block-bounding fault that developed during this episode divide the deformed rocks of the quadrangle into major structural plates and tilted blocks in and east of the Chemehuevi Mountains core complex. The low-angle faults attenuate crustal section, superposing supracrustal and upper crustal rocks against gneisses and granitoids originally from deeper crustal levels. The transverse block-bounding Gold Dome Fault Zone juxtaposes two large hanging-wall blocks, each tilted 90°, and the fault zone splays at its tip into folds in layered Miocene rocks. A synfaulting intrusion occupies the triangular zone where the folded strata detached from an inside corner along this fault between the tilt blocks. Post-extensional upper Miocene to Quaternary strata, locally deformed, record post-extensional landscape evolution, including several Pliocene and younger aggradational episodes in the Colorado River valley and intervening degradation episodes. The aggradational sequences include (1) the Bouse Formation, (2) fluvial deposits correlated with the alluvium of Bullhead City, (3) the younger fluvial boulder conglomerate of Bat Cave Wash, (4) the fluvial Chemehuevi Formation and related valley-margin deposits, and (5) fluvial Holocene deposits under the river and the valley floor. These fluvial records of Colorado River deposition are interspersed with piedmont alluvial fan deposits of several ages.

New allocyclic dimensions in a prograding carbonate bank: Evidence for eustatic, tectonic, and paleoceanographic control (late Neogene, Bahamas)

USGS Publications Warehouse

Lidz, B.H.; McNeill, D.F.

1997-01-01

The deep-sea record, examined recently for the first time in a shallow-depocenter setting, has unveiled remarkable evidence for new sedimentary components and allocyclic complexity in a large, well-studied carbonate bank, the western Great Bahama Bank. The evidence is a composite foraminiferal signature - Paleocene to early Miocene (allogenic or reworked) and late Miocene to late Pliocene (host) planktic taxa, and redeposited middle Miocene shallow benthic faunas. Ages of the oldest and youngest planktic groups range from ??? 66 to ??? 2 Ma. The reworked and redeposited taxa are a proxy for significant sediment components that otherwise have no lithofacies or seismic resolution. The composite signature, reinforced by a distinctive distribution of the reworked and redeposited faunas, documents a much more complex late Neogene depositional system than previously known. The system is more than progradational. The source sequences that supplied the constituent bank-margin grains formed at different water depths and over hundreds of kilometers and tens of millions of years apart. New evidence from the literature and from data obtained during Ocean Drilling Program (OOP) Leg 166 in the Santaren Channel (Bahamas) support early interpretations based on the composite fossil record and provide valuable new dimensions to regional allocyclicity. The middle Miocene taxa were confined to the lower part of the section by the latest Miocene-earliest Pliocene(?) lowstand of sea level. An orderly occurrence of the allogenic taxa is unique to the global reworked geologic record and appears to have been controlled by a combination of Paleogene-early Neogene tectonics at the source, eustatic changes, and late Neogene current activity at the source and across the bank. The allogenic taxa expand the spatial and temporal range of information in the northern Bahamas by nearly an order of magnitude. In essence, some of the major processes active in the region during ??? 64 m.y. of the Cenozoic can be viewed from within a narrow (??? 6 m.y.) late Neogene window. In this case, the fossil record also serves to demonstrate the potential and significance in evaluating reworked and redeposited assemblages. Copyright ?? 1998, SEPM (Society for Sedimentary Geology).

Historical Reconstruction Reveals Recovery in Hawaiian Coral Reefs

PubMed Central

Kittinger, John N.; Pandolfi, John M.; Blodgett, Jonathan H.; Hunt, Terry L.; Jiang, Hong; Maly, Kepā; McClenachan, Loren E.; Schultz, Jennifer K.; Wilcox, Bruce A.

2011-01-01

Coral reef ecosystems are declining worldwide, yet regional differences in the trajectories, timing and extent of degradation highlight the need for in-depth regional case studies to understand the factors that contribute to either ecosystem sustainability or decline. We reconstructed social-ecological interactions in Hawaiian coral reef environments over 700 years using detailed datasets on ecological conditions, proximate anthropogenic stressor regimes and social change. Here we report previously undetected recovery periods in Hawaiian coral reefs, including a historical recovery in the MHI (∼AD 1400–1820) and an ongoing recovery in the NWHI (∼AD 1950–2009+). These recovery periods appear to be attributed to a complex set of changes in underlying social systems, which served to release reefs from direct anthropogenic stressor regimes. Recovery at the ecosystem level is associated with reductions in stressors over long time periods (decades+) and large spatial scales (>103 km2). Our results challenge conventional assumptions and reported findings that human impacts to ecosystems are cumulative and lead only to long-term trajectories of environmental decline. In contrast, recovery periods reveal that human societies have interacted sustainably with coral reef environments over long time periods, and that degraded ecosystems may still retain the adaptive capacity and resilience to recover from human impacts. PMID:21991311

Coral reef grazer-benthos dynamics complicated by invasive algae in a small marine reserve

PubMed Central

Stamoulis, Kostantinos A.; Friedlander, Alan M.; Meyer, Carl G.; Fernandez-Silva, Iria; Toonen, Robert J.

2017-01-01

Blooms of alien invasive marine algae have become common, greatly altering the health and stability of nearshore marine ecosystems. Concurrently, herbivorous fishes have been severely overfished in many locations worldwide, contributing to increases in macroalgal cover. We used a multi-pronged, interdisciplinary approach to test if higher biomass of herbivorous fishes inside a no-take marine reserve makes this area more resistant to invasive algal overgrowth. Over a two year time period, we (1) compared fish biomass and algal cover between two fished and one unfished patch reef in Hawai’i, (2) used acoustic telemetry to determine fidelity of herbivorous fishes to the unfished reef, and (3) used metabarcoding and next-generation sequencing to determine diet composition of herbivorous fishes. Herbivore fish biomass was significantly higher in the marine reserve compared to adjacent fished reefs, whereas invasive algal cover differed by species. Herbivorous fish movements were largely confined to the unfished patch reef where they were captured. Diet analysis indicated that the consumption of invasive algae varied among fish species, with a high prevalence of comparatively rare native algal species. Together these findings demonstrate that the contribution of herbivores to coral reef resilience, via resistance to invasive algae invasion, is complex and species-specific. PMID:28276458

Modeling Hydrodynamics on the Wave Group Scale in Topographically Complex Reef Environments

NASA Astrophysics Data System (ADS)

Reyns, J.; Becker, J. M.; Merrifield, M. A.; Roelvink, J. A.

2016-02-01

The knowledge of the characteristics of waves and the associated wave-driven currents is important for sediment transport and morphodynamics, nutrient dynamics and larval dispersion within coral reef ecosystems. Reef-lined coasts differ from sandy beaches in that they have a steep offshore slope, that the non-sandy bottom topography is very rough, and that the distance between the point of maximum short wave dissipation and the actual coastline is usually large. At this short wave breakpoint, long waves are released, and these infragravity (IG) scale motions account for the bulk of the water level variance on the reef flat, the lagoon and eventually, the sandy beaches fronting the coast through run-up. These IG energy dominated water level motions are reinforced during extreme events such as cyclones or swells through larger incident band wave heights and low frequency wave resonance on the reef. Recently, a number of hydro(-morpho)dynamic models that have the capability to model these IG waves have successfully been applied to morphologically differing reef environments. One of these models is the XBeach model, which is curvilinear in nature. This poses serious problems when trying to model an entire atoll for example, as it is extremely difficult to build curvilinear grids that are optimal for the simulation of hydrodynamic processes, while maintaining the topology in the grid. One solution to remediate this problem of grid connectivity is the use of unstructured grids. We present an implementation of the wave action balance on the wave group scale with feedback to the flow momentum balance, which is the foundation of XBeach, within the framework of the unstructured Delft3D Flexible Mesh model. The model can be run in stationary as well as in instationary mode, and it can be forced by regular waves, time series or wave spectra. We show how the code is capable of modeling the wave generated flow at a number of topographically complex reef sites and for a number of different forcing conditions, by comparison with field data.

Applying New Methods to Diagnose Coral Diseases

USGS Publications Warehouse

Kellogg, Christina A.; Zawada, David G.

2009-01-01

Coral disease, one of the major causes of reef degradation and coral death, has been increasing worldwide since the 1970s, particularly in the Caribbean. Despite increased scientific study, simple questions about the extent of disease outbreaks and the causative agents remain unanswered. A component of the U.S. Geological Survey Coral Reef Ecosystem STudies (USGS CREST) project is focused on developing and using new methods to approach the complex problem of coral disease.

Complementarity of Rotating Video and Underwater Visual Census for Assessing Species Richness, Frequency and Density of Reef Fish on Coral Reef Slopes

PubMed Central

Mallet, Delphine; Wantiez, Laurent; Lemouellic, Soazig; Vigliola, Laurent; Pelletier, Dominique

2014-01-01

Estimating diversity and abundance of fish species is fundamental for understanding community structure and dynamics of coral reefs. When designing a sampling protocol, one crucial step is the choice of the most suitable sampling technique which is a compromise between the questions addressed, the available means and the precision required. The objective of this study is to compare the ability to sample reef fish communities at the same locations using two techniques based on the same stationary point count method: one using Underwater Visual Census (UVC) and the other rotating video (STAVIRO). UVC and STAVIRO observations were carried out on the exact same 26 points on the reef slope of an intermediate reef and the associated inner barrier reefs. STAVIRO systems were always deployed 30 min to 1 hour after UVC and set exactly at the same place. Our study shows that; (i) fish community observations by UVC and STAVIRO differed significantly; (ii) species richness and density of large species were not significantly different between techniques; (iii) species richness and density of small species were higher for UVC; (iv) density of fished species was higher for STAVIRO and (v) only UVC detected significant differences in fish assemblage structure across reef type at the spatial scale studied. We recommend that the two techniques should be used in a complementary way to survey a large area within a short period of time. UVC may census reef fish within complex habitats or in very shallow areas such as reef flat whereas STAVIRO would enable carrying out a large number of stations focused on large and diver-averse species, particularly in the areas not covered by UVC due to time and depth constraints. This methodology would considerably increase the spatial coverage and replication level of fish monitoring surveys. PMID:24392126

Major Sources of Organic Matter in a Complex Coral Reef Lagoon: Identification from Isotopic Signatures (δ13C and δ15N)

PubMed Central

Briand, Marine J.; Bonnet, Xavier; Goiran, Claire; Guillou, Gaël; Letourneur, Yves

2015-01-01

A wide investigation was conducted into the main organic matter (OM) sources supporting coral reef trophic networks in the lagoon of New Caledonia. Sampling included different reef locations (fringing, intermediate and barrier reef), different associated ecosystems (mangroves and seagrass beds) and rivers. In total, 30 taxa of macrophytes, plus pools of particulate and sedimentary OM (POM and SOM) were sampled. Isotopic signatures (C and N) of each OM sources was characterized and the composition of OM pools assessed. In addition, spatial and seasonal variations of reef OM sources were examined. Mangroves isotopic signatures were the most C-depleted (-30.17 ± 0.41 ‰) and seagrass signatures were the most C-enriched (-4.36 ± 0.72 ‰). Trichodesmium spp. had the most N-depleted signatures (-0.14 ± 0.03 ‰) whereas mangroves had the most N-enriched signatures (6.47 ± 0.41 ‰). The composition of POM and SOM varied along a coast-to-barrier reef gradient. River POM and marine POM contributed equally to coastal POM, whereas marine POM represented 90% of the POM on barrier reefs, compared to 10% river POM. The relative importance of river POM, marine POM and mangroves to the SOM pool decreased from fringing to barrier reefs. Conversely, the relative importance of seagrass, Trichodesmium spp. and macroalgae increased along this gradient. Overall, spatial fluctuations in POM and SOM were much greater than in primary producers. Seasonal fluctuations were low for all OM sources. Our results demonstrated that a large variety of OM sources sustain coral reefs, varying in their origin, composition and role and suggest that δ13C was a more useful fingerprint than δ15N in this endeavour. This study also suggested substantial OM exchanges and trophic connections between coral reefs and surrounding ecosystems. Finally, the importance of accounting for environmental characteristics at small temporal and spatial scales before drawing general patterns is highlighted. PMID:26134985

Science and management of coral reefs: problems and prospects

NASA Astrophysics Data System (ADS)

Wells, S. M.

1995-11-01

It should be recognised that many principles of reef management do not need further research, as they involve changing human behaviour and activities in order to remove or reduce impacts on reefs. Much of the time of a reef manager is taken up with social, economic and political issues: the integration of reef management into broad coastal zone management objectives; the development of community participation and co-management; and the organisation of training and education pro-grammes so that people in countries where reefs are located are able to take responsibility for their sustainable management. Perhaps the main obstacle to be overcome is poor communication (Harmon 1994). Many reef scientists are already strongly convinced of the need to communicate their results and the implications of these for management and conservation policy (Hatcher et al. 1989), but they may however need to understand that reef managers are not always able or willing to act on their advice because of political, economic or social factors. Pure research is increasingly being conducted within a framework of goals identified as important to society. Funding is invariably easier to obtain if it can be demonstrated that the research will have some ultimate benefit in management terms, and much research is being commissioned because of the need for practical solutions. As the complexity of management becomes more apparent and managers themselves call for more scientific support and advice, the role that science has to play in perceiving and defining problems, understanding the mechanisms involved and strategically assessing potential solutions, becomes more central. Often, only a slight adjustment to a project is required in order for data to be collected that is of direct value to a reef manager.Partnerships built between scientists and managers engaged in adaptive management efforts may lead to more rapid progress in managing reefs and may banish the `science and management' dichotomy once and for all.

A new Miocene baleen whale from the Peruvian desert

NASA Astrophysics Data System (ADS)

Marx, Felix G.; Kohno, Naoki

2016-10-01

The Pisco-Ica and Sacaco basins of southern Peru are renowned for their abundance of exceptionally preserved fossil cetaceans, several of which retain traces of soft tissue and occasionally even stomach contents. Previous work has mostly focused on odontocetes, with baleen whales currently being restricted to just three described taxa. Here, we report a new Late Miocene rorqual (family Balaenopteridae), Incakujira anillodefuego gen. et sp. nov., based on two exceptionally preserved specimens from the Pisco Formation exposed at Aguada de Lomas, Sacaco Basin, southern Peru. Incakujira overall closely resembles modern balaenopterids, but stands out for its unusually gracile ascending process of the maxilla, as well as a markedly twisted postglenoid process of the squamosal. The latter likely impeded lateral (omega) rotation of the mandible, in stark contrast with the highly flexible craniomandibular joint of extant lunge-feeding rorquals. Overall, Incakujira expands the still meagre Miocene record of balaenopterids and reveals a previously underappreciated degree of complexity in the evolution of their iconic lunge-feeding strategy.

Petroleum systems of the Malay Basin Province, Malaysia

USGS Publications Warehouse

Bishop, Michele G.

2002-01-01

The offshore Malay Basin province is a Tertiary oil and gas province composed of a complex of half grabens that were filled by lacustrine shales and continental clastics.These deposits were overlain by clastics of a large delta system that covered the basin.Delta progradation was interupted by transgressions of the South China Sea to the southeast, which finally flooded the basin to form the Gulf of Thailand.Oil and gas from the Oligocene to Miocene lacustrine shales and Miocene deltaic coals is trapped primarily in anticlines formed by inversion of the half grabens during the late Miocene.Hydrocarbon reserves that have been discovered amount to 12 billion barrels of oil equivalent.The U.S. Geological Survey assessment of the estimated quantities of conventional oil, gas and condensate that have the potential to be added to reserves by the year 2025 for this province is 6.3 billion barrels of oil equivalent (BBOE) (U. S. Geological Survey World Energy Assessment Team, 2000).

Dental remains of cebid platyrrhines from the earliest late Miocene of Western Amazonia, Peru: Macroevolutionary implications on the extant capuchin and marmoset lineages.

PubMed

Marivaux, Laurent; Adnet, Sylvain; Altamirano-Sierra, Ali J; Pujos, François; Ramdarshan, Anusha; Salas-Gismondi, Rodolfo; Tejada-Lara, Julia V; Antoine, Pierre-Olivier

2016-11-01

Undoubted fossil Cebidae have so far been primarily documented from the late middle Miocene of Colombia, the late Miocene of Brazilian Amazonia, the early Miocene of Peruvian Amazonia, and very recently from the earliest Miocene of Panama. The evolutionary history of cebids is far from being well-documented, with notably a complete blank in the record of callitrichine stem lineages until and after the late middle Miocene (Laventan SALMA). Further documenting their evolutionary history is therefore of primary importance. Recent field efforts in Peruvian Amazonia (Contamana area, Loreto Department) have allowed for the discovery of an early late Miocene (ca. 11 Ma; Mayoan SALMA) fossil primate-bearing locality (CTA-43; Pebas Formation). In this study, we analyze the primate material, which consists of five isolated teeth documenting two distinct Cebidae: Cebus sp., a medium-sized capuchin (Cebinae), and Cebuella sp., a tiny marmoset (Callitrichinae). Although limited, this new fossil material of platyrrhines contributes to documenting the post-Laventan evolutionary history of cebids, and besides testifies to the earliest occurrences of the modern Cebuella and Cebus/Sapajus lineages in the Neotropics. Regarding the evolutionary history of callitrichine marmosets, the discovery of an 11 Ma-old fossil representative of the modern Cebuella pushes back by at least 6 Ma the age of the Mico/Cebuella divergence currently proposed by molecular biologists (i.e., ca. 4.5 Ma). This also extends back to > 11 Ma BP the divergence between Callithrix and the common ancestor (CA) of Mico/Cebuella, as well as the divergence between the CA of marmosets and Callimico (Goeldi's callitrichine). This discovery from Peruvian Amazonia implies a deep evolutionary root of the Cebuella lineage in the northwestern part of South America (the modern western Amazon basin), slightly before the recession of the Pebas mega-wetland system (PMWS), ca. 10.5 Ma, and well-before the subsequent establishment of the Amazon drainage system (ca. 9-7 Ma). During the late middle/early late Miocene interval, the PMWS was seemingly not a limiting factor for dispersals and widespread distribution of terrestrial mammals, but it was also likely a source of diversification via a complex patchwork of submerged/emerged lands varying through time. © 2016 Wiley Periodicals, Inc.

An extensive reef system at the Amazon River mouth

PubMed Central

Moura, Rodrigo L.; Amado-Filho, Gilberto M.; Moraes, Fernando C.; Brasileiro, Poliana S.; Salomon, Paulo S.; Mahiques, Michel M.; Bastos, Alex C.; Almeida, Marcelo G.; Silva, Jomar M.; Araujo, Beatriz F.; Brito, Frederico P.; Rangel, Thiago P.; Oliveira, Braulio C. V.; Bahia, Ricardo G.; Paranhos, Rodolfo P.; Dias, Rodolfo J. S.; Siegle, Eduardo; Figueiredo, Alberto G.; Pereira, Renato C.; Leal, Camille V.; Hajdu, Eduardo; Asp, Nils E.; Gregoracci, Gustavo B.; Neumann-Leitão, Sigrid; Yager, Patricia L.; Francini-Filho, Ronaldo B.; Fróes, Adriana; Campeão, Mariana; Silva, Bruno S.; Moreira, Ana P. B.; Oliveira, Louisi; Soares, Ana C.; Araujo, Lais; Oliveira, Nara L.; Teixeira, João B.; Valle, Rogerio A. B.; Thompson, Cristiane C.; Rezende, Carlos E.; Thompson, Fabiano L.

2016-01-01

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 106–km2 plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume’s eastward retroflection, conditions the existence of this extensive (~9500 km2) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth–ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes. PMID:27152336

The demise of a major Acropora palmata bank-barrier reef off the southeast coast of Barbados, West Indies

NASA Astrophysics Data System (ADS)

MacIntyre, I. G.; Glynn, P. W.; Toscano, M. A.

2007-12-01

Formerly attributed to human activity, the demise of a bank-barrier reef off southeastern Barbados known as Cobbler’s Reef is now thought to be largely the result of late Holocene, millennial-scale storm damage. Eleven surface samples of the reef crest coral Acropora palmata from nine sites along its 15-km length plot above the western Atlantic sea-level curve from 3,000 to 4,500 cal years ago (calibrated, calendar 14C years). These elevated clusters suggest that the reef complex suffered extensive storm damage during this period. The constant heavy wave action typical of this area and consequent low herbivory maintain conditions favoring algal growth, thereby limiting the reestablishment of post-storm reef framework. Site descriptions and detailed line surveys show a surface now composed mainly of reworked fragments of A. palmata covered with algal turf, macroalgae and crustose coralline algae. The reef contains no live A. palmata and only a few scattered coral colonies consisting primarily of Diploria spp . and Porites astreoides, along with the hydrocoral Millepora complanata. A few in situ framework dates plot at expected depths for normal coral growth below the sea-level curve during and after the period of intense storm activity. The most recent of these in situ samples are 320 and 400 cal years old. Corals of this late period likely succumbed to high turbidity associated with land clearance for sugarcane agriculture in the mid-1600s.

Understanding the spatial distribution of subtidal reef assemblages in the southern Baltic Sea using towed camera platform imagery

NASA Astrophysics Data System (ADS)

Beisiegel, Kolja; Darr, Alexander; Zettler, Michael L.; Friedland, René; Gräwe, Ulf; Gogina, Mayya

2018-07-01

Quantitative sampling of sessile assemblages on temperate subtidal rocky reefs is expensive and severely time-limited by logistics. However, knowledge about distribution patterns of critical and endangered species and habitats at different spatial scales is needed for effective marine management strategies. To gain information of sessile community distribution on broader spatial scales (>1 km), visual imaging was employed for the first time on a reef complex in the south-western Baltic Sea. Analysis of 3000 images along 6 transects (in total 18 km long) from 10 to 40 m depth revealed high natural variation in reef physical structure, with well-defined changes in sessile species richness, cover and composition. Overall 14 morphological groups could be distinguished by imaging and 4 distinct community groups associated with specific habitat requirements were identified. Depth remained the best descriptor. However, data indicate that light intensity, concentration of organic carbon and suspended particulate matter have an effect on reef community distribution. Compared to fully marine conditions, the study revealed a unique zonation pattern in the circalittoral zone of the Fehmarnbelt brackish transition area, with an unexpected reef habitat in the trench. We conclude that towed camera platform imagery might help to close the information gap regarding rocky reefs in the temperate subtidal. It provides a valuable tool to assess the main distribution patterns of sessile assemblages on rough terrain, potentially applicable for management and conservation planning.

Secondary calcification and dissolution respond differently to future ocean conditions

NASA Astrophysics Data System (ADS)

Silbiger, N. J.; Donahue, M. J.

2015-01-01

Climate change threatens both the accretion and erosion processes that sustain coral reefs. Secondary calcification, bioerosion, and reef dissolution are integral to the structural complexity and long-term persistence of coral reefs, yet these processes have received less research attention than reef accretion by corals. In this study, we use climate scenarios from RCP 8.5 to examine the combined effects of rising ocean acidity and sea surface temperature (SST) on both secondary calcification and dissolution rates of a natural coral rubble community using a flow-through aquarium system. We found that secondary reef calcification and dissolution responded differently to the combined effect of pCO2 and temperature. Calcification had a non-linear response to the combined effect of pCO2 and temperature: the highest calcification rate occurred slightly above ambient conditions and the lowest calcification rate was in the highest temperature-pCO2 condition. In contrast, dissolution increased linearly with temperature-pCO2 . The rubble community switched from net calcification to net dissolution at +271 μatm pCO2 and 0.75 °C above ambient conditions, suggesting that rubble reefs may shift from net calcification to net dissolution before the end of the century. Our results indicate that (i) dissolution may be more sensitive to climate change than calcification and (ii) that calcification and dissolution have different functional responses to climate stressors; this highlights the need to study the effects of climate stressors on both calcification and dissolution to predict future changes in coral reefs.

Secondary calcification and dissolution respond differently to future ocean conditions

NASA Astrophysics Data System (ADS)

Silbiger, N. J.; Donahue, M. J.

2014-09-01

Climate change threatens both the accretion and erosion processes that sustain coral reefs. Secondary calcification, bioerosion, and reef dissolution are integral to the structural complexity and long-term persistence of coral reefs, yet these processes have received less research attention than reef accretion by corals. In this study, we use climate scenarios from RCP8.5 to examine the combined effects of rising ocean acidity and SST on both secondary calcification and dissolution rates of a natural coral rubble community using a flow-through aquarium system. We found that secondary reef calcification and dissolution responded differently to the combined effect of pCO2 and temperature. Calcification had a non-linear response to the combined effect of pCO2-temperature: the highest calcification rate occurred slightly above ambient conditions and the lowest calcification rate was in the highest pCO2-temperature condition. In contrast, dissolution increased linearly with pCO2-temperature. The rubble community switched from net calcification to net dissolution at +272 μatm pCO2 and 0.84 °C above ambient conditions, suggesting that rubble reefs may shift from net calcification to net dissolution before the end of the century. Our results indicate that dissolution may be more sensitive to climate change than calcification, and that calcification and dissolution have different functional responses to climate stressors, highlighting the need to study the effects of climate stressors on both calcification and dissolution to predict future changes in coral reefs.

An extensive reef system at the Amazon River mouth.

PubMed

Moura, Rodrigo L; Amado-Filho, Gilberto M; Moraes, Fernando C; Brasileiro, Poliana S; Salomon, Paulo S; Mahiques, Michel M; Bastos, Alex C; Almeida, Marcelo G; Silva, Jomar M; Araujo, Beatriz F; Brito, Frederico P; Rangel, Thiago P; Oliveira, Braulio C V; Bahia, Ricardo G; Paranhos, Rodolfo P; Dias, Rodolfo J S; Siegle, Eduardo; Figueiredo, Alberto G; Pereira, Renato C; Leal, Camille V; Hajdu, Eduardo; Asp, Nils E; Gregoracci, Gustavo B; Neumann-Leitão, Sigrid; Yager, Patricia L; Francini-Filho, Ronaldo B; Fróes, Adriana; Campeão, Mariana; Silva, Bruno S; Moreira, Ana P B; Oliveira, Louisi; Soares, Ana C; Araujo, Lais; Oliveira, Nara L; Teixeira, João B; Valle, Rogerio A B; Thompson, Cristiane C; Rezende, Carlos E; Thompson, Fabiano L

2016-04-01

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (~9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.

Predatory fish depletion and recovery potential on Caribbean reefs

PubMed Central

Valdivia, Abel; Cox, Courtney Ellen; Bruno, John Francis

2017-01-01

The natural, prehuman abundance of most large predators is unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomass at a given location (that is, the predator carrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reef fish biomass and several anthropogenic and environmental variables at 39 reefs across the Caribbean to (i) estimate their roles determining local predator biomass and (ii) determine site-specific recovery potential if fishing was eliminated. We show that predatory reef fish biomass tends to be higher in marine reserves but is strongly negatively related to human activities, especially coastal development. However, human activities and natural factors, including reef complexity and prey abundance, explain more than 50% of the spatial variation in predator biomass. Comparing site-specific predator carrying capacities to field observations, we infer that current predatory reef fish biomass is 60 to 90% lower than the potential supportable biomass in most sites, even within most marine reserves. We also found that the scope for recovery varies among reefs by at least an order of magnitude. This suggests that we could underestimate unfished biomass at sites that provide ideal conditions for predators or greatly overestimate that of seemingly predator-depleted sites that may have never supported large predator populations because of suboptimal environmental conditions. PMID:28275730

iss016e019394

NASA Image and Video Library

2008-05-02

ISS016-E-019394 (30 Dec. 2007) --- Al Wadj Bank, Saudi Arabia is featured in this image photographed by an Expedition 16 crewmember on the International Space Station. Saudi Arabia boasts the most coral reefs of any Middle Eastern country, as it includes coastline along both the Red Sea and Gulf of Arabia. This high resolution image depicts a portion of the Al Wadj Bank, located along the northern Red Sea coast. Despite the relatively high salinity of Red Sea water (compared to other oceans), approximately 260 species of coral are found here, according to scientists. Large tracts of the Saudi Arabian coastline are undeveloped, and reefs in these areas are in generally good ecological health. However, reefs located near large urban centers like Jeddeh have suffered degradation due to land reclamation, pollution, and increased terrigeneous sediment input. The Al Wadj Bank includes a healthy and diverse reef system, extensive seagrass beds, and perhaps the largest population of dugong -- a marine mammal similar to the North American manatee -- in the eastern Red Sea. The portion of the Bank in this image illustrates the complex form and topography of the reef system. Several emergent islands (tan) - surrounded primarily by dark green seagrass - are visible, the largest located at top left. Only the islands are above the waterline -- over the reef structures the water color ranges from light teal (shallow) to turquoise (increasing depth). The southern edge of the reef is well indicated by the deep, dark blue water of the Red Sea at image top.

Exploring Spatiotemporal Trends in Commercial Fishing Effort of an Abalone Fishing Zone: A GIS-Based Hotspot Model

PubMed Central

Jalali, M. Ali; Ierodiaconou, Daniel; Gorfine, Harry; Monk, Jacquomo; Rattray, Alex

2015-01-01

Assessing patterns of fisheries activity at a scale related to resource exploitation has received particular attention in recent times. However, acquiring data about the distribution and spatiotemporal allocation of catch and fishing effort in small scale benthic fisheries remains challenging. Here, we used GIS-based spatio-statistical models to investigate the footprint of commercial diving events on blacklip abalone (Haliotis rubra) stocks along the south-west coast of Victoria, Australia from 2008 to 2011. Using abalone catch data matched with GPS location we found catch per unit of fishing effort (CPUE) was not uniformly spatially and temporally distributed across the study area. Spatial autocorrelation and hotspot analysis revealed significant spatiotemporal clusters of CPUE (with distance thresholds of 100’s of meters) among years, indicating the presence of CPUE hotspots focused on specific reefs. Cumulative hotspot maps indicated that certain reef complexes were consistently targeted across years but with varying intensity, however often a relatively small proportion of the full reef extent was targeted. Integrating CPUE with remotely-sensed light detection and ranging (LiDAR) derived bathymetry data using generalized additive mixed model corroborated that fishing pressure primarily coincided with shallow, rugose and complex components of reef structures. This study demonstrates that a geospatial approach is efficient in detecting patterns and trends in commercial fishing effort and its association with seafloor characteristics. PMID:25992800

Genome-Based Analyses of Six Hexacorallian Species Reject the "Naked Coral" Hypothesis.

PubMed

Wang, Xin; Drillon, Guénola; Ryu, Taewoo; Voolstra, Christian R; Aranda, Manuel

2017-10-01

Scleractinian corals are the foundation species of the coral-reef ecosystem. Their calcium carbonate skeletons form extensive structures that are home to millions of species, making coral reefs one of the most diverse ecosystems of our planet. However, our understanding of how reef-building corals have evolved the ability to calcify and become the ecosystem builders they are today is hampered by uncertain relationships within their subclass Hexacorallia. Corallimorpharians have been proposed to originate from a complex scleractinian ancestor that lost the ability to calcify in response to increasing ocean acidification, suggesting the possibility for corals to lose and gain the ability to calcify in response to increasing ocean acidification. Here, we employed a phylogenomic approach using whole-genome data from six hexacorallian species to resolve the evolutionary relationship between reef-building corals and their noncalcifying relatives. Phylogenetic analysis based on 1,421 single-copy orthologs, as well as gene presence/absence and synteny information, converged on the same topologies, showing strong support for scleractinian monophyly and a corallimorpharian sister clade. Our broad phylogenomic approach using sequence-based and sequence-independent analyses provides unambiguous evidence for the monophyly of scleractinian corals and the rejection of corallimorpharians as descendants of a complex coral ancestor. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

3D structure of a complex of transform basins from gravity data, a case study from the central Dead Sea fault

NASA Astrophysics Data System (ADS)

Rosenthal, Michal; Schattner, Uri; Ben-Avraham, Zvi

2017-04-01

The Kinneret-Bet She'an (KBS) basin complex comprises the Sea of Galilee, Kinarot, and Bet She'an sub-basins. The complex developed at the intersection between two major tectonic boundaries: the Oligo-Miocene Azraq-Sirhan failed rift, that later developed into the southern Galilee basins and Carmel-Gilboa fault system; and the Dead Sea fault (DSF) plate boundary that developed since the Miocene. Despite numerous studies, KBS still remains one of the enigmatic basin complexes. Its structure, stratigraphy and development are vaguely understood - both inside the basin and in correlation with its surroundings. Our study presents a new and comprehensive 3D model for the structure of KBS complex. It is based on all available gravity measurements, adopted from the national gravity database, and new gravity measurements, collected in cooperation with the Geological Survey of Israel and funded by the Ministry of National Infrastructure, Energy and Water Resources. The gravity data were integrated with constraints from boreholes, surface geology, seismic surveys, potential field studies and teleseismic tomography. The dense distribution of gravity data [1] provides suitable coverage for modeling the deep structure in three dimensions. The model details the spatial distribution, depth, thickness and density of the following regional units within the KBS complex and across its surroundings: upper crust, pre-Senonian sediments, Senonian and Cenozoic sediments, Miocene volcanics, Pliocene and Quaternary volcanics. Additional local units include salt, gabbro and pyroclasts. Results indicate that the KBS complex comprises two sub-basins separated by a structural saddle: Kinneret-Kinarot ( 6-7 km deep, 45 km long) and Bet She'an ( 4 km deep, 10 km long) sub-basin. A 500 m thick layer of Miocene volcanics appears across the Bet She'an sub-basin, yet missing from the Kinneret-Kinarot sub-basin. Between the basins Zemah-1 borehole penetrated a salt unit. The model indicates that this unit is a part of a thick (1250 m) dome-shaped, perhaps diapiric, structure. A relatively thin (350 m) salt unit fills the Kinneret-Kinarot sub-basin. Above, a 700 m thick layer of Pliocene volcanics fills the entire KBS complex. These volcanics are uplifted in the Zemah area by 200 m. The Pliocene volcanics dip northward from Zemah towards the center of the Sea of Galilee, and further north the Pliocene volcanics dip southward from Korazim towards the center of the Sea of Galilee. The depth differences exceed 3 km across a distance of 15 km, forming a 11° slope below the younger Quaternary fill of the basin. A low-density, probably pyroclastic, lens is calculated within the uppermost 2 km of the Sea of Galilee fill. Scenarios for the development of the basin are discussed. [1] Rosenthal, M., Segev, A., Rybakov, M., Lyakhovsky, V. and Ben-Avraham, Z. (2015) The deep structure and density distribution of northern Israel and its surroundings. GSI Report No. GSI/12/2015, 33 pages, Jerusalem.

Commercial coral-reef fisheries across Micronesia: A need for improving management

NASA Astrophysics Data System (ADS)

Houk, P.; Rhodes, K.; Cuetos-Bueno, J.; Lindfield, S.; Fread, V.; McIlwain, J. L.

2012-03-01

A dearth of scientific data surrounding Micronesia's coral-reef fisheries has limited their formal assessment and continues to hinder local and regional management efforts. We approach this problem by comparing catch-based datasets from market landings across Micronesia to evaluate fishery status in the Commonwealth of the Northern Mariana Islands (CNMI), Guam, Yap, and Pohnpei. Initial examinations found that calm weather and low lunar illumination predicted between 6% (Yap) and 30% (CNMI) of the variances in daily commercial landings. Both environmentally driven catch success and daily catch variability increased in accordance with reef-fish demand indices. Subsequent insight from species composition and size-at-capture data supported these findings, highlighting reduced trophic levels and capture sizes where higher human-population-per-reef-area existed. Among the 12-15 target species and/or species complexes that accounted for 70% of the harvest biomass, capture sizes were consistently smallest for CNMI and Guam, often below the reported mean reproductive sizes. Comparatively, Pohnpei has the greatest potential for reef fisheries, with a large reef area (303 km2) and a moderate human population (34,000 people). However, the estimated harvest volume of 476 mt year-1 was 8-9 times higher than other jurisdictions. Even on Yap where the reef-fish demand index was lowest (67.7 people km-2 reef habitat), many target fish were harvested below their mean reproductive sizes, including the iconic green bumphead parrotfish and humphead wrasse, as well as several other herbivores. We discuss our results with respect to the contemporary doctrine surrounding size-spectra, catch composition, and catch frequencies that afford insight into fishery pressure and status. We posit that regional catch-based policies (initially) instituted at the market level, combined with area and gear-based restrictions, represent plausible vectors for improving Micronesian fisheries.

Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems.

PubMed

Graham, Nicholas A J; McClanahan, Tim R; MacNeil, M Aaron; Wilson, Shaun K; Polunin, Nicholas V C; Jennings, Simon; Chabanet, Pascale; Clark, Susan; Spalding, Mark D; Letourneur, Yves; Bigot, Lionel; Galzin, René; Ohman, Marcus C; Garpe, Kajsa C; Edwards, Alasdair J; Sheppard, Charles R C

2008-08-27

Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.

Filling the gaps: Predicting the distribution of temperate reef biota using high resolution biological and acoustic data

NASA Astrophysics Data System (ADS)

Hill, Nicole A.; Lucieer, Vanessa; Barrett, Neville S.; Anderson, Tara J.; Williams, Stefan B.

2014-06-01

Management of the marine environment is often hampered by a lack of comprehensive spatial information on the distribution of diversity and the bio-physical processes structuring regional ecosystems. This is particularly true in temperate reef systems beyond depths easily accessible to divers. Yet these systems harbor a diversity of sessile life that provide essential ecosystem services, sustain fisheries and, as with shallower ecosystems, are also increasingly vulnerable to anthropogenic impacts and environmental change. Here we use cutting-edge tools (Autonomous Underwater Vehicles and ship-borne acoustics) and analytical approaches (predictive modelling) to quantify and map these highly productive ecosystems. We find the occurrence of key temperate-reef biota can be explained and predicted using standard (depth) and novel (texture) surrogates derived from multibeam acoustic data, and geographic surrogates. This suggests that combinations of fine-scale processes, such as light limitation and habitat complexity, and broad-scale processes, such as regional currents and exposure regimes, are important in structuring these diverse deep-reef communities. While some dominant habitat forming biota, including canopy algae, were widely distributed, others, including gorgonians and sea whips, exhibited patchy and restricted distributions across the reef system. In addition to providing the first quantitative and full coverage maps of reef diversity for this area, our modelling revealed that offshore reefs represented a regional diversity hotspot that is of high ecological and conservation value. Regional reef systems should not, therefore, be considered homogenous units in conservation planning and management. Full-coverage maps of the predicted distribution of biota (and associated uncertainty) are likely to be increasingly valuable, not only for conservation planning, but in the ongoing management and monitoring of these less-accessible ecosystems.

Multibeam mapping of the Pinnacles region, Gulf of Mexico

USGS Publications Warehouse

Gardner, James V.; Dartnell, Peter; Sulak, Kenneth J.

2002-01-01

Recent USGS mapping shows an extensive deep (~100 m) reef tract occurs on the Mississippi-Alabama outer continental shelf (Figure 1). The tract, known as "The Pinnacles", is apparently part of a sequence of drowned reef complexes along the "40-fathom" shelf edge of the northern Gulf of Mexico (Ludwick and Walton, 1957). It is critical to determine the accurate geomorphology of these deep-reefs because of their importance as benthic habitats for fisheries. The Pinnacles have previously been mapped using a single-beam echo sounder (Ludwick and Walton,1957), sidescan sonar (Laswell et al., 1990), and the TAMU2 towed single-beam sidescan-sonar system (Anonymous, 1999). These existing studies do not provide the quality of geomorphic data necessary for reasonable habitat studies.

A key phase in the recruitment dynamics of coral reef fishes: post-settlement transition

USGS Publications Warehouse

Kaufman, L.; Ebersole, J.L.; Beets, Jim; McIvor, Carole

1992-01-01

Recent studies of recruitment dynamics in demersal fishes have placed major emphasis on presettlement mortality, and little on events bridging late larval and early juvenile periods. Observations on 68 taxa of Caribbean coral reef fishes before and during settlement revealed the existence of a distinct post-settlement life phase called the transition juvenile, associated with the act of recruitment. Transition juveniles were found as solitary individuals, in conspecific groups, or in heterospecific groups. The groups were either uniform or heterogenous in appearance. The complexity of the transition phase and its apparently widespread occurrence in coral reef fishes suggests that important aspects of population structure may be determined between settlement and first appearance as a full-fledged juvenile.

Timing, distribution, amount, and style of Cenozoic extension in the northern Great Basin

USGS Publications Warehouse

Henry, Christopher D.; McGrew, Allen J.; Colgan, Joseph P.; Snoke, Arthur W.; Brueseke, Matthew E.

2011-01-01

This field trip examines contrasting lines of evidence bearing on the timing and structural style of Cenozoic (and perhaps late Mesozoic) extensional deformation in northeastern Nevada. Studies of metamorphic core complexes in this region report extension beginning in the early Cenozoic or even Late Cretaceous, peaking in the Eocene and Oligocene, and being largely over before the onset of “modern” Basin and Range extension in the middle Miocene. In contrast, studies based on low-temperature thermochronology and geologic mapping of Eocene and Miocene volcanic and sedimentary deposits report only minor, localized extension in the Eocene, no extension at all in the Oligocene and early Miocene, and major, regional extension in the middle Miocene. A wealth of thermochronologic and thermobarometric data indicate that the Ruby Mountains–East Humboldt Range metamorphic core complex (RMEH) underwent ~170 °C of cooling and 4 kbar of decompression between ca. 85 and ca. 50 Ma, and another 450 °C cooling and 4–5 kbar decompression between ca. 50 and ca. 21 Ma. These data require ~30 km of exhumation in at least two episodes, accommodated at least in part by Eocene to early Miocene displacement on the major west-dipping mylonitic zone and detachment fault bounding the RMEH on the west (the mylonitic zone may also have been active during an earlier phase of crustal extension). Meanwhile, Eocene paleovalleys containing 45–40 Ma ash-flow tuffs drained eastward from northern Nevada to the Uinta Basin in Utah, and continuity of these paleovalleys and infilling tuffs across the region indicate little, if any deformation by faults during their deposition. Pre–45 Ma deformation is less constrained, but the absence of Cenozoic sedimentary deposits and mappable normal faults older than 45 Ma is also consistent with only minor (if any) brittle deformation. The presence of ≤1 km of late Eocene sedimentary—especially lacustrine—deposits and a low-angle angular unconformity between ca. 40 and 38 Ma rocks attest to an episode of normal faulting at ca. 40 Ma. Arguably the greatest conundrum is how much extension occurred between ca. 35 and 17 Ma. Major exhumation of the RMEH is interpreted to have taken place in the late Oligocene and early Miocene, but rocks of any kind deposited during this interval are scarce in northeastern Nevada and absent in the vicinity of the RMEH itself. In most places, no angular unconformity is present between late Eocene and middle Miocene rocks, indicating little or no tilting between the late Eocene and middle Miocene. Opinions among authors of this report differ, however, as to whether this indicates no extension during the same time interval. The one locality where Oligocene deposits have been documented is Copper Basin, where Oligocene (32.5–29.5 Ma) conglomerates are ~500 m thick. The contact between Oligocene and Eocene rocks in Copper Basin is conformable, and the rocks are uniformly tilted ~25° NW, opposite to a normal fault system dipping ~35° SE. Middle Miocene rhyolite (ca. 16 Ma) rests nonconformably on the metamorphosed lower plate of this fault system and appears to rest on the tilted upper-plate rocks with angular unconformity, but the contact is not physically exposed. Different authors of this report interpret geologic relations in Copper Basin to indicate either (1) significant episodes of extension in the Eocene, Oligocene, and middle Miocene or (2) minor extension in the Eocene, uncertainty about the Oligocene, and major extension in the middle Miocene. An episode of major middle Miocene extension beginning at ca. 16–17 Ma is indicated by thick (up to 5 km) accumulations of sedimentary deposits in half-graben basins over most of northern Nevada, tilting and fanning of dips in the synextensional sedimentary deposits, and apatite fission-track and (U-Th)/He data from the southern Ruby Mountains and other ranges that indicate rapid middle Miocene cooling through near-surface temperatures (~120–40 °C). Opinions among authors of this report differ as to whether this period of extension was merely the last step in a long history of extensional faulting dating back at least to the Eocene, or whether it accounts for most of the Cenozoic deformation in northeastern Nevada. Since 10–12 Ma, extension appears to have slowed greatly and been accommodated by high-angle, relatively wide-spaced normal faults that give topographic form to the modern ranges. Despite the low present-day rate of extension, normal faults are active and have generated damaging earthquakes as recently as 2008.

Characterizing a complex aquifer system using geophysics, hydrodynamics and geochemistry: A new distribution of Miocene aquifers in the Zéramdine and Mahdia-Jébéniana blocks (east-central Tunisia)

NASA Astrophysics Data System (ADS)

Lachaal, Fethi; Bédir, Mourad; Tarhouni, Jamila; Gacha, Ayadi Ben; Leduc, Christian

2011-06-01

The Zéramdine and Mahdia-Jébéniana blocks are located in the Sahel region in east-central Tunisia. Active tectonics have divided the region into numerous sub-units, as result of multiple phases of distension and compression. The Miocene fluvio-deltaic sediment sandy layers have aquiferous capacities but their hydraulic properties are still unknown, due to the lack of investigation wells. This study proposes a new description of the regional hydrogeology of Miocene deposits. Seismic-reflection and wireline logging of petroleum and water wells were used to understand the structure and the geometry of the Miocene reservoirs. The groundwater flow and its relationship to the sedimentary and tectonic context were then identified by studying piezometry and hydrochemistry. Two Miocene deep aquifer systems were identified: (1) Zéramdine-Béni Hassen to the north and (2) Jébéniana-Ksour Essef to the south. These aquifers are separated by the Mahdia graben. Other major tectonic structures, such as the Zéramdine fault corridor, the Moknine graben, and the El-Jem half-graben represent lateral boundaries for these aquifers. Other deeper sandy and clayey-sandy reservoirs were also identified in the area. Their repartition, thickness and depth vary from one block to other. Hydrodynamics of the deep aquifers seems to be controlled by geological structures. Two independent compartments were identified: in the northern block groundwater flows from West to East and from Northwest to Southeast, while in the southern block it flows from Northwest to Southeast. Geochemical facies are of two types: Na-Ca-Cl-SO 4 for the Zéramdine-Béni Hassen deep aquifer and Na-Cl for the Jébéniana-Ksour Essef deep aquifer. The hydrodynamic and geochemical results confirm the sharing of the Miocene sediments into two aquifers.

End of the chain? Rugosity and fine-scale bathymetry from existing underwater digital imagery using structure-from-motion (SfM) technology

USGS Publications Warehouse

Storlazzi, Curt; Dartnell, Peter; Hatcher, Gerry; Gibbs, Ann E.

2016-01-01

The rugosity or complexity of the seafloor has been shown to be an important ecological parameter for fish, algae, and corals. Historically, rugosity has been measured either using simple and subjective manual methods such as ‘chain-and-tape’ or complicated and expensive geophysical methods. Here, we demonstrate the application of structure-from-motion (SfM) photogrammetry to generate high-resolution, three-dimensional bathymetric models of a fringing reef from existing underwater video collected to characterize the seafloor. SfM techniques are capable of achieving spatial resolution that can be orders of magnitude greater than large-scale lidar and sonar mapping of coral reef ecosystems. The resulting data provide finer-scale measurements of bathymetry and rugosity that are more applicable to ecological studies of coral reefs than provided by the more expensive and time-consuming geophysical methods. Utilizing SfM techniques for characterizing the benthic habitat proved to be more effective and quantitatively powerful than conventional methods and thus might portend the end of the ‘chain-and-tape’ method for measuring benthic complexity.

Determination of aluminium in groundwater samples by GF-AAS, ICP-AES, ICP-MS and modelling of inorganic aluminium complexes.

PubMed

Frankowski, Marcin; Zioła-Frankowska, Anetta; Kurzyca, Iwona; Novotný, Karel; Vaculovič, Tomas; Kanický, Viktor; Siepak, Marcin; Siepak, Jerzy

2011-11-01

The paper presents the results of aluminium determinations in ground water samples of the Miocene aquifer from the area of the city of Poznań (Poland). The determined aluminium content amounted from <0.0001 to 752.7 μg L(-1). The aluminium determinations were performed using three analytical techniques: graphite furnace atomic absorption spectrometry (GF-AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The results of aluminium determinations in groundwater samples for particular analytical techniques were compared. The results were used to identify the ascent of ground water from the Mesozoic aquifer to the Miocene aquifer in the area of the fault graben. Using the Mineql+ program, the modelling of the occurrence of aluminium and the following aluminium complexes: hydroxy, with fluorides and sulphates was performed. The paper presents the results of aluminium determinations in ground water using different analytical techniques as well as the chemical modelling in the Mineql+ program, which was performed for the first time and which enabled the identification of aluminium complexes in the investigated samples. The study confirms the occurrence of aluminium hydroxy complexes and aluminium fluoride complexes in the analysed groundwater samples. Despite the dominance of sulphates and organic matter in the sample, major participation of the complexes with these ligands was not stated based on the modelling.

Artificial Reefs Created by Electrolysis and Coral Transplantation: An Approach Ensuring the Compatibility of Environmental Protection and Diving Tourism

NASA Astrophysics Data System (ADS)

van Treeck, P.; Schuhmacher, H.

1999-08-01

Coral reefs are currently being subjected to increasing pressure caused by water sports, especially scuba diving. Highly complex reef coenoses are affected by mechanical breakage and the coverage of corals by resuspended sediments. As the ecological capacity of the biocoenosis is exceeded, sensitive species are suppressed and the community is impoverished. The conflict between the needs of nature conservation and the economic interests of diving tourism can be mitigated by the creation of artificial underwater attractions as reef substitutes. Specially designed underwater structures are ideal for many diving activities, which can be diverted from sensitive natural habitats in that way. It is also possible to develop model reef communities for training and environmental education purposes. Our new concept is based on the elegant solution, proposed by Hilbertz et al. (1977), of depositing calcium minerals from the seawater in situ by electrolysis. We report on experiments conducted near Aqaba (Red Sea) showing that it is feasible to transplant living coral fragments on to the substrate being developed by electrochemical processes. In this way, the formation of a diverse community on any structure desired can be considerably enhanced.

Water Column Correction for Coral Reef Studies by Remote Sensing

PubMed Central

Zoffoli, Maria Laura; Frouin, Robert; Kampel, Milton

2014-01-01

Human activity and natural climate trends constitute a major threat to coral reefs worldwide. Models predict a significant reduction in reef spatial extension together with a decline in biodiversity in the relatively near future. In this context, monitoring programs to detect changes in reef ecosystems are essential. In recent years, coral reef mapping using remote sensing data has benefited from instruments with better resolution and computational advances in storage and processing capabilities. However, the water column represents an additional complexity when extracting information from submerged substrates by remote sensing that demands a correction of its effect. In this article, the basic concepts of bottom substrate remote sensing and water column interference are presented. A compendium of methodologies developed to reduce water column effects in coral ecosystems studied by remote sensing that include their salient features, advantages and drawbacks is provided. Finally, algorithms to retrieve the bottom reflectance are applied to simulated data and actual remote sensing imagery and their performance is compared. The available methods are not able to completely eliminate the water column effect, but they can minimize its influence. Choosing the best method depends on the marine environment, available input data and desired outcome or scientific application. PMID:25215941

Water column correction for coral reef studies by remote sensing.

PubMed

Zoffoli, Maria Laura; Frouin, Robert; Kampel, Milton

2014-09-11

Human activity and natural climate trends constitute a major threat to coral reefs worldwide. Models predict a significant reduction in reef spatial extension together with a decline in biodiversity in the relatively near future. In this context, monitoring programs to detect changes in reef ecosystems are essential. In recent years, coral reef mapping using remote sensing data has benefited from instruments with better resolution and computational advances in storage and processing capabilities. However, the water column represents an additional complexity when extracting information from submerged substrates by remote sensing that demands a correction of its effect. In this article, the basic concepts of bottom substrate remote sensing and water column interference are presented. A compendium of methodologies developed to reduce water column effects in coral ecosystems studied by remote sensing that include their salient features, advantages and drawbacks is provided. Finally, algorithms to retrieve the bottom reflectance are applied to simulated data and actual remote sensing imagery and their performance is compared. The available methods are not able to completely eliminate the water column effect, but they can minimize its influence. Choosing the best method depends on the marine environment, available input data and desired outcome or scientific application.

The fishes of Cayo Arcas (Campeche Bank, Gulf of Mexico): an updated checklist.

PubMed

Robertson, D Ross; Perez-España, Horacio; Lara, Enrique Nuñez; Itza, Francisco Puc; Simoes, Nuno

2016-01-01

Cayo Arcas is a small, offshore reef complex on the southwest corner of Campeche Bank, Gulf of Mexico. The only published information (from 2000) on the fishes of that reef refers to 37 species. Here additional information is added, some from unpublished observations during the 1980s, as well as author observations made during 2013 and 2016. These bring the checklist of that reef's fishes up to 162 species. The possible effects of the limited number of fish habitats available at Cayo Arcas on the composition of its fish fauna are discussed. The Indo-Pacific damselfish Neopomacentrus cyanomos (Bleeker, 1856) was first recorded in the Atlantic in mid-2013, on shoreline reefs in the southwest corner of the Gulf of Mexico. Recently reviewed underwater photographs show that Neopomacentrus cyanomos also was present at Cayo Arcas in mid-2013, 350 km from the first-record site. Hence it evidently had a substantial population in the southwest Gulf of Mexico in 2013, and must have arrived in there long before that year.

Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years

NASA Astrophysics Data System (ADS)

Meissner, K. J.; Lippmann, T.; Sen Gupta, A.

2012-06-01

One-third of the world's coral reefs have disappeared over the last 30 years, and a further third is under threat today from various stress factors. The main global stress factors on coral reefs have been identified as changes in sea surface temperature (SST) and changes in surface seawater aragonite saturation (Ωarag). Here, we use a climate model of intermediate complexity, which includes an ocean general circulation model and a fully coupled carbon cycle, in conjunction with present-day observations of inter-annual SST variability to investigate three IPCC representative concentration pathways (RCP 3PD, RCP 4.5, and RCP 8.5), and their impact on the environmental stressors of coral reefs related to open ocean SST and open ocean Ωarag over the next 400 years. Our simulations show that for the RCP 4.5 and 8.5 scenarios, the threshold of 3.3 for zonal and annual mean Ωarag would be crossed in the first half of this century. By year 2030, 66-85% of the reef locations considered in this study would experience severe bleaching events at least once every 10 years. Regardless of the concentration pathway, virtually every reef considered in this study (>97%) would experience severe thermal stress by year 2050. In all our simulations, changes in surface seawater aragonite saturation lead changes in temperatures.

Geomorphological diversity of Dong-Sha Atoll based on spectrum and texture analysis in high resolution remote sensing imagery

NASA Astrophysics Data System (ADS)

Chen, Jianyu; Mao, Zhihua; He, Xianqiang

2009-01-01

Coral reefs are complex marine ecosystems that are constructed and maintained by biological communities that thrive in tropical oceans. The Dong-Sha Atoll is located at the northern continental margin of the South China Sea. It has being abused by destructive activity of human being and natural event during recent decades. Remote sensing offers a powerful tool for studying coral reef geomorphology and is the most cost-effective approach for large-scale reef survey. In this paper, the high-resolution Quickbird2 imageries which covered the full atoll are used to categorize the current distribution of coral reefs geomorphological structure therein with the auxiliary SPOT5 and ASTER imageries. Spectral and texture analysis are used to distinguish the geomorphological diversity during data processing. The Gray Level Co-occurrence Matrices is adopted for texture feature extraction and atoll geomorphology mapping in the high-resolution pan-color image of Quickbird2. Quickbird2 is considered as the most appropriate image source for coral reefs studies. In the Dong-Sha Atoll, various dynamical geomorphologic units are developed according to wave energy zones. There the reef frame types are classified to 3 different types according as its diversity at the image. The radial structure system is the most characteristic and from high resolution imagery we can distinguish the discrepancy between them.

An outline of tectonic, igneous, and metamorphic events in the Goshute-Toano Range between Silver Zone Pass and White Horse Pass, Elko County, Nevada; a history of superposed contractional and extensional deformation

USGS Publications Warehouse

Ketner, Keith Brindley; Day, Warren C.; Elrick, Maya; Vaag, Myra K.; Zimmerman, Robert A.; Snee, Lawrence W.; Saltus, Richard W.; Repetski, John E.; Wardlaw, Bruce R.; Taylor, Michael E.; Harris, Anita G.

1998-01-01

Seven kinds of fault-bounded tracts are described. One of the tracts provides a good example of Mesozoic contractional folding and faulting; six exemplify various aspects of Miocene extensional faulting. Massive landslide deposits resulting from Tertiary faulting are described. Mesozoic intrusive rocks and extensive exposures of Miocene volcanic rocks are described and dated. The age ranges of stratigraphic units were based on numerous conodont collections, and ages of igneous rocks were determined by argon/argon and fission-track methods. The geologic complexity of the Goshute-Toano Range provides opportunities for many additional productive structural studies.

An Analysis of Artificial Reef Fish Community Structure along the Northwestern Gulf of Mexico Shelf: Potential Impacts of “Rigs-to-Reefs” Programs

PubMed Central

Ajemian, Matthew J.; Wetz, Jennifer J.; Shipley-Lozano, Brooke; Shively, J. Dale; Stunz, Gregory W.

2015-01-01

Artificial structures are the dominant complex marine habitat type along the northwestern Gulf of Mexico (GOM) shelf. These habitats can consist of a variety of materials, but in this region are primarily comprised of active and reefed oil and gas platforms. Despite being established for several decades, the fish communities inhabiting these structures remain poorly investigated. Between 2012 and 2013 we assessed fish communities at 15 sites using remotely operated vehicles (ROVs). Fish assemblages were quantified from standing platforms and an array of artificial reef types (Liberty Ships and partially removed or toppled platforms) distributed over the Texas continental shelf. The depth gradient covered by the surveys (30–84 m) and variability in structure density and relief also permitted analyses of the effects of these characteristics on fish richness, diversity, and assemblage composition. ROVs captured a variety of species inhabiting these reefs from large transient piscivores to small herbivorous reef fishes. While structure type and relief were shown to influence species richness and community structure, major trends in species composition were largely explained by the bottom depth where these structures occurred. We observed a shift in fish communities and relatively high diversity at approximately 60 m bottom depth, confirming trends observed in previous studies of standing platforms. This depth was also correlated with some of the largest Red Snapper captured on supplementary vertical longline surveys. Our work indicates that managers of artificial reefing programs (e.g., Rigs-to-Reefs) in the GOM should carefully consider the ambient environmental conditions when designing reef sites. For the Texas continental shelf, reefing materials at a 50–60 m bottom depth can serve a dual purpose of enhancing diving experiences and providing the best potential habitat for relatively large Red Snapper. PMID:25954943

The impact of exploiting grazers (Scaridae) on the dynamics of Caribbean coral reefs.

PubMed

Mumby, Peter J

2006-04-01

Coral reefs provide a number of ecosystem services including coastal defense from storms, the generation of building materials, and fisheries. It is increasingly clear that the management of reef resources requires an ecosystem approach in which extractive activities are weighed against the needs of the ecosystem and its functions rather than solely those of the fishery. Here, I use a spatially explicit simulation model of a Caribbean coral reef to examine the ecosystem requirements for grazing which is primarily conducted by parrotfishes (Scaridae). The model allows the impact of fishing grazers to be assessed in the wider context of other ecosystem processes including coral-algal competition, hurricanes, and mass extinction of the herbivorous urchin Diadema antillarum. Using a new analytical model of scarid grazing, it is estimated that parrotfishes can only maintain between 10% and 30% of a structurally complex forereef in a grazed state. Predictions from this grazing model were then incorporated into a broader simulation model of the ecosystem. Simulations predict that scarid grazing is unable to maintain high levels of coral cover (> or = 30%) when severe hurricanes occur on a decadal basis, such as occurs in parts of the northern Caribbean. However, reefs can withstand such intense disturbance when grazing is undertaken by both scarids and the urchin Diadema. Scarid grazing is predicted to allow recovery from hurricanes when their incidence falls to 20 years or less (e.g., most of Central and South America). Sensitivity analyses revealed that scarid grazing had the most acute impact on model behavior, and depletion led to the emergence of a stable, algal-dominated community state. Under conditions of heavy grazer depletion, coral cover was predicted to decline rapidly from an initial level of 30% to less than 1% within 40 years, even when hurricane frequency was low at 60 years. Depleted grazers caused a population bottleneck in juvenile corals in which algal overgrowth caused elevated levels of postsettlement mortality and resulted in a bimodal distribution of coral sizes. Several new hypotheses were generated including a region-wide change in the spatial heterogeneity of coral reefs following extinction of Diadema. The management of parrotfishes on Caribbean reefs is usually approached implicitly through no-take marine reserves. The model predicts that depletion of grazers in nonreserve areas can severely limit coral accretion. Other studies have shown that low coral accretion can reduce the structural complexity and therefore quality of the reef habitat for many organisms. A speculative yet rational inference from the model is that failure to manage scarid populations outside reserves will have a profoundly negative impact on the functioning of the reserve system and status of non-reserve reefs.

Quantitative morphology of a fringing reef tract from high-resolution laser bathymetry: Southern Molokai, Hawaii

USGS Publications Warehouse

Storlazzi, C.D.; Logan, J.B.; Field, M.E.

2003-01-01

High-resolution Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) laser-determined bathymetric data were used to define the morphology of spur-and-groove structures on the fringing reef off the south coast of Molokai, Hawaii. These data provide a basis for mapping and analyzing morphology of the reef with a level of precision and spatial coverage never before attained. An extensive fringing coral reef stretches along the central two-thirds of Molokai's south shore (???40 km); along the east and west ends there is only a thin veneer of living coral with no developed reef complex. In total, ???4800 measurements of spur-and-groove height and the distance between adjacent spur crests (wavelength) were obtained along four isobaths. Between the 5m and 15m isobaths, the mean spur height increased from 0.7 m to 1.6 m, whereas the mean wavelength increased from 71 m to 104 m. Reef flat width was found to exponentially decrease with increasing wave energy. Overall, mean spur-and-groove height and wavelength were shown to be inversely proportional to wave energy. In high-energy environments, spur-and-groove morphology remains relatively constant across all water depths. In low-energy environments, however, spur-and-groove structures display much greater variation; they are relatively small and narrow in shallow depths and develop into much larger and broader features in deeper water. Therefore, it appears that waves exert a primary control on both the small and large-scale morphology of the reef off south Molokai.

Application of Reflectance Transformation Imaging Technique to Improve Automated Edge Detection in a Fossilized Oyster Reef

NASA Astrophysics Data System (ADS)

Djuricic, Ana; Puttonen, Eetu; Harzhauser, Mathias; Dorninger, Peter; Székely, Balázs; Mandic, Oleg; Nothegger, Clemens; Molnár, Gábor; Pfeifer, Norbert

2016-04-01

The world's largest fossilized oyster reef is located in Stetten, Lower Austria excavated during field campaigns of the Natural History Museum Vienna between 2005 and 2008. It is studied in paleontology to learn about change in climate from past events. In order to support this study, a laser scanning and photogrammetric campaign was organized in 2014 for 3D documentation of the large and complex site. The 3D point clouds and high resolution images from this field campaign are visualized by photogrammetric methods in form of digital surface models (DSM, 1 mm resolution) and orthophoto (0.5 mm resolution) to help paleontological interpretation of data. Due to size of the reef, automated analysis techniques are needed to interpret all digital data obtained from the field. One of the key components in successful automation is detection of oyster shell edges. We have tested Reflectance Transformation Imaging (RTI) to visualize the reef data sets for end-users through a cultural heritage viewing interface (RTIViewer). The implementation includes a Lambert shading method to visualize DSMs derived from terrestrial laser scanning using scientific software OPALS. In contrast to shaded RTI no devices consisting of a hardware system with LED lights, or a body to rotate the light source around the object are needed. The gray value for a given shaded pixel is related to the angle between light source and the normal at that position. Brighter values correspond to the slope surfaces facing the light source. Increasing of zenith angle results in internal shading all over the reef surface. In total, oyster reef surface contains 81 DSMs with 3 m x 2 m each. Their surface was illuminated by moving the virtual sun every 30 degrees (12 azimuth angles from 20-350) and every 20 degrees (4 zenith angles from 20-80). This technique provides paleontologists an interactive approach to virtually inspect the oyster reef, and to interpret the shell surface by changing the light source direction. One source of light for shading does show all morphologic features needed for description. Additionally, more details such as fault lines, overlaps and characteristic edges of complex shell structures are clearly detected by simply changing the illumination on the shaded digital surface model. In a further study, the potential of edge detection of the individual shells will be analyzed based on statistical analysis by keeping track of the local accumulative shading gradient. The results are compared to manually identified edges. In a following study phase, the detected edges will be improved by graph cut segmentation. We assume that this technique can lead to automatically extracted teaching set for object segmentation on a complex environment. The project is supported by the Austrian Science Fund (FWF P 25883-N29).

Kinematics of Faulting and Structural Evolution of Neogene Supra-detachment Basins on the Menderes Metamorphic Core Complex, Western Anatolia

NASA Astrophysics Data System (ADS)

Dilek, Y.; Oner, Z.; Davis, E. A.

2007-12-01

The Menderes metamorphic massif (MM) in western Anatolia is a classic core complex with exhumed high-grade crustal rocks intruded by granodioritic plutons and overlain by syn-extensional sedimentary rocks. Timing and the mechanism(s) of the initial exhumation of the MM are controversial, and different hypotheses exist in the literature. Major structural grabens (i.e. Alasehir, Buyuk Menderes) within the MM that are bounded by high-angle and seismically active faults are late-stage brittle structures, which characterize the block-faulting phase in the extensional history of the core complex and are filled with Quaternary sediments. On the southern shoulder of the Alasehir graben high-grade metamorphic rocks of the MM are overlain by the Miocene and younger sedimentary rocks above a N-dipping detachment surface. The nearly 100-m-thick cataclastic shear zone beneath this surface contain S-C fabrics, microfaults, Riedel shears, mica-fish structures and shear bands, all consistently indicating top-to-the North shearing. Granodioritic plutons crosscutting the MM and the detachment surface are exposed within this cataclastic zone, displaying extensional ductile and brittle structures. The oldest sedimentary rocks onlapping the cataclastic shear zone of the MM here are the Middle Miocene lacustrine shale and limestone units, unconformably overlain by the Upper Miocene fluvial and alluvial fan deposits. Extensive development of these alluvial fan deposits by the Late Miocene indicates the onset of range-front faulting in the MM by this time, causing a surge of coarse clastic deposition along the northern edge of the core complex. The continued exhumation and uplift of the MM provided the necessary relief and detrital material for the Plio-Pleistocene fluvial systems in the Alasehir supradetachment basin (ASDB). A combination of rotational normal faulting and scissor faulting in the extending ASDB affected the depositional patterns and drainage systems, and produced local unconformities within the basinal stratigraphy. High-angle, oblique-slip scissor faults crosscutting the MM rocks, the detachment surface and the basinal strata offset them for more than few 100 meters and the fault blocks locally show different structural architecture and metamorphic grades, suggesting differential uplift along these scissor faults. This fault kinematics and the distribution of range-parallel and range-perpendicular faults strongly controlled the shape and depth of the accommodation space within the ASDB. At a more regional scale scissor faulting across the MM seems to have controlled the foci of Plio-Pleistocene point-source volcanism in the Aegean extensional province (e.g. Kula area). There are no major interruptions in the syn-extensional depositional history of the ASDB, ruling out the pulsed-extension models suggesting a period of contractional deformation in the late Cenozoic evolution of the MM. The onset of exhumation and extensional tectonics in the MM and western Anatolia was a result of thermal weakening of the orogenic crust, following a widespread episode of post-collisional magmatism in the broader Aegean region during the Eocene through Miocene.

The legacy of a vanished sea: a high level of diversification within a European freshwater amphipod species complex driven by 15 My of Paratethys regression.

PubMed

Mamos, Tomasz; Wattier, Remi; Burzyński, Artur; Grabowski, Michał

2016-02-01

The formation of continental Europe in the Neogene was due to the regression of the Tethys Ocean and of the Paratethys Sea. The dynamic geology of the area and repetitious transitions between marine and freshwater conditions presented opportunities for the colonization of newly emerging hydrological networks and diversification of aquatic biota. Implementing mitochondrial and nuclear markers in conjunction with a large-scale sampling strategy, we investigated the impact of this spatiotemporal framework on the evolutionary history of a freshwater crustacean morphospecies. The Gammarus balcanicus species complex is widely distributed in the area previously occupied by the Paratethys Sea. Our results revealed its high diversification and polyphyly in relation to a number of other morphospecies. The distribution of the studied amphipod is generally characterized by very high local endemism and divergence. The Bayesian time-calibrated reconstruction of phylogeny and geographical distribution of ancestral nodes indicates that this species complex started to diversify in the Early Miocene in the central Balkans, partially in the shallow epicontinental sea. It is possible that there were several episodes of inland water colonization by local brackish water lineages. Subsequent diversification within clades and spread to new areas could have been induced by Alpine orogeny in the Miocene/Pliocene and, finally, by Pleistocene glaciations. The present distribution of clades, in many cases, still reflects Miocene palaeogeography of the area. Our results point out that investigations of the historical aspect of cryptic diversity in other taxa may help in a general understanding of the origins of freshwater invertebrate fauna of Europe. © 2015 John Wiley & Sons Ltd.

Cenozoic granitoids in the Dinarides of southern Serbia: age of intrusion, isotope geochemistry, exhumation history and significance for the geodynamic evolution of the Balkan Peninsula

NASA Astrophysics Data System (ADS)

Schefer, Senecio; Cvetković, Vladica; Fügenschuh, Bernhard; Kounov, Alexandre; Ovtcharova, Maria; Schaltegger, Urs; Schmid, Stefan M.

2011-07-01

Two age groups were determined for the Cenozoic granitoids in the Dinarides of southern Serbia by high-precision single grain U-Pb dating of thermally annealed and chemically abraded zircons: (1) Oligocene ages (Kopaonik, Drenje, Željin) ranging from 31.7 to 30.6 Ma (2) Miocene ages (Golija and Polumir) at 20.58-20.17 and 18.06-17.74 Ma, respectively. Apatite fission-track central ages, modelling combined with zircon central ages and additionally, local structural observations constrain the subsequent exhumation history of the magmatic rocks. They indicate rapid cooling from above 300°C to ca. 80°C between 16 and 10 Ma for both age groups, induced by extensional exhumation of the plutons located in the footwall of core complexes. Hence, Miocene magmatism and core-complex formation not only affected the Pannonian basin but also a part of the mountainous areas of the internal Dinarides. Based on an extensive set of existing age data combined with our own analyses, we propose a geodynamical model for the Balkan Peninsula: The Late Eocene to Oligocene magmatism, which affects the Adria-derived lower plate units of the internal Dinarides, was caused by delamination of the Adriatic mantle from the overlying crust, associated with post-collisional convergence that propagated outward into the external Dinarides. Miocene magmatism, on the other hand, is associated with core-complex formation along the southern margin of the Pannonian basin, probably associated with the W-directed subduction of the European lithosphere beneath the Carpathians and interfering with ongoing Dinaridic-Hellenic back-arc extension.

Morphological characterization of coral reefs by combining lidar and MBES data: A case study from Yuanzhi Island, South China Sea

NASA Astrophysics Data System (ADS)

Zhang, Kai; Yang, Fanlin; Zhang, Hande; Su, Dianpeng; Li, QianQian

2017-06-01

The correlation between seafloor morphological features and biological complexity has been identified in numerous recent studies. This research focused on the potential for accurate characterization of coral reefs based on high-resolution bathymetry from multiple sources. A standard deviation (STD) based method for quantitatively characterizing terrain complexity was developed that includes robust estimation to correct for irregular bathymetry and a calibration for the depth-dependent variablity of measurement noise. Airborne lidar and shipborne sonar bathymetry measurements from Yuanzhi Island, South China Sea, were merged to generate seamless high-resolution coverage of coral bathymetry from the shoreline to deep water. The new algorithm was applied to the Yuanzhi Island surveys to generate maps of quantitive terrain complexity, which were then compared to in situ video observations of coral abundance. The terrain complexity parameter is significantly correlated with seafloor coral abundance, demonstrating the potential for accurately and efficiently mapping coral abundance through seafloor surveys, including combinations of surveys using different sensors.

Complex basin evolution in the Gökova Gulf region: implications on the Late Cenozoic tectonics of southwest Turkey

NASA Astrophysics Data System (ADS)

Gürer, Ömer Feyzi; Sanğu, Ercan; Özburan, Muzaffer; Gürbüz, Alper; Sarica-Filoreau, Nuran

2013-11-01

Southwestern Turkey experienced a transition from crustal shortening to extension during Late Cenozoic, and evidence of this was recorded in four distinct basin types in the Muğla-Gökova Gulf region. During the Oligocene-Early Miocene, the upper slices of the southerly moving Lycian Nappes turned into north-dipping normal faults due to the acceleration of gravity. The Kale-Tavas Basin developed as a piggyback basin along the fault plane on hanging wall blocks of these normal faults. During Middle Miocene, a shift had occurred from local extension to N-S compression/transpression, during which sediments in the Eskihisar-Tınaz Basins were deposited in pull-apart regions of the Menderes Massif cover units, where nappe slices were already eroded. During the Late Miocene-Pliocene, a hiatus occurred from previous compressional/transpressional tectonism along intermountain basins and Yatağan Basin fills were deposited on Menderes Massif, Lycian Nappes, and on top of Oligo-Miocene sediments. Plio-Quaternary marked the activation of N-S extension and the development of the E-W-trending Muğla-Gökova Grabens, co-genetic equivalents of which are common throughout western Anatolia. Thus, the tectonic evolution of the western Anotolia during late Cenozoic was shifting from compressional to extensional with a relaxation period, suggesting a non-uniform evolution.

Tertiary stratigraphy and basin evolution, southern Sabah (Malaysian Borneo)

NASA Astrophysics Data System (ADS)

Balaguru, Allagu; Nichols, Gary

2004-08-01

New mapping and dating of strata in the southern part of the Central Sabah Basin in northern Borneo has made it possible to revise the lithostratigraphy and chronostratigraphy of the area. The recognition in the field of an Early Miocene regional unconformity, which may be equivalent to the Deep Regional Unconformity recognised offshore, has allowed the development of a stratigraphic framework of groups and formations, which correspond to stages in the sedimentary basin development of the area. Below the Early Miocene unconformity lies ophiolitic basement, which is overlain by an accretionary complex of Eocene age and a late Paleogene deep water succession which formed in a fore-arc basin. The late Paleogene deposits underwent syn-depositional deformation, including the development of extensive melanges, all of which can be demonstrated to lie below the unconformity in this area. Some localised limestone deposition occurred during a period of uplift and erosion in the Early Miocene, following which there was an influx of clastic sediments deposited in delta and pro-deltaic environments in the Middle Miocene. These deltaic to shallow marine deposits are now recognised as forming two coarsening-upward successions, mapped as the Tanjong and Kapilit Formations. The total thickness of these two formations in the Central Sabah Basin amounts to 6000 m, only half of the previous estimates, although the total stratigraphic thickness of Cenozoic clastic strata in Sabah may be more than 20,000 m.

Chemical changes and carbon isotope variations in a cross-section of a large Miocene gymnospermous log

USGS Publications Warehouse

Bates, A.L.; Spiker, E. C.

1992-01-01

The cross-sectional radius of a 3-m (diam.) brown coal gymnospermous log of Miocene age, previously analyzed for carbohydrate and lignin methoxyl content by solid-state 13C nuclear magnetic resonance spectroscopy, was examined using stable carbon isotopic ratios in order to determine if the isotopic composition could be related to chemical changes or to radial position. This study found a possible relationship between ??13C-values and radial position; however, these changes cannot be linked to carbohydrate content and are probably attributable to changing growth conditions during the lifetime of the tree. An apparent linear relationship between the changes in carbohydrate content after sodium para-periodate treatment and corresponding changes in the ??13C-values indicates constant isotopic fractionation between lignin and carbohydrates along the cross-sectional radius. This result indicates that diagenesis has not produced any significant change in the lignin-carbohydrate carbon isotopic fractionation or, alternatively, that diagenesis has erased any fractionation pattern that once existed. A sample of fresh wood from another gymnospermous species was analyzed by the same methods and found to have lignin-carbohydrate carbon isotopic fractionation significantly different from that of the Miocene log section samples, suggesting that differences may be species-related or that the complex mixture of carbohydrates in the fresh wood was isotopically different from that of the degraded wood, and the whole Miocene log was uniformly altered. ?? 1992.

TIMS U-series dating and stable isotopes of the last interglacial event in Papua New Guinea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stein, M.; Wasserburg, G.J.; Chen, J.H.

1993-06-01

The extensive flight of uplifted reef terraces which occurs along the Vitiaz strait on the northern flank of the Huon Peninsula in PNG (Papua New Guinea) contains a particularly good record of sea level changes in the last 250 ky. The Huon terraces were the target of an international expedition which took place in July--August 1988. In particular, the authors searched for suitable samples for U-series dating in a reef complex designated as VII, which is correlated with the last interglacial episode and high sea level stand. This complex is composed of a barrier reef (VIIb), a lagoon, and amore » fringing reef (VIIa). Twelve corals from these terraces and two corals from the older reef complex VIII were selected for analysis. The petrography, oxygen and carbon isotope compositions, and magnesium and strontium concentrations were determined along with the concentrations and isotopic compositions of uranium and thorium. The simplest model for sea level height for terrace VII is a continuous rise between 134 and 118 ky. Alternatively, there may have been two periods of rapid sea level rise. In contrast, in the Bahamas, there is evidence that sea level remained rather constant over the time interval 132 to 120 ky. The absence of ages between 132 and 120 ky in PNG could be the result of changes in the local tectonic uplift rates during that time, or erosion that disrupted the continuous record. In any event, the authors find no basis for accepting a single brief time for the age of the last interglacial and applying this age as a precise chronometer for worldwide correlation, or as a test of climatic models. The older ages reported here precede the Milankovitch solar insolation peak at 128 ky, and the younger ages are [approximately]10 ky after this peak. If the present high-precision data are correct, then it will be necessary to reassess the validity of the Milankovitch theory of climatic changes. 76 refs., 6 figs., 6 tabs.« less

Miocene tectonics of the Western Alboran domain: from mantle extensional exhumation to westward thrusting

NASA Astrophysics Data System (ADS)

Gueydan, F.; Frasca, G.; Brun, J. P.

2015-12-01

In the frame of the Africa-Europe convergence, the Mediterranean tectonic system presents a complex interaction between subduction rollback and upper-plate deformation during the Tertiary. The western Mediterranean is characterized by the exhumation of the largest subcontinental mantle massif worldwide (the Ronda Peridotite) and a narrow arcuate geometryacross the Gibraltar arc within the Betic-Rif belt (the internal part being called the Alboran domain), where the relationship between slab dynamics and surface tectonics is not well understood. New structural and geochronological data are used to argue for 1/ hyperstrechting of the continental lithosphere allowing extensional mantle exhumation to shallow depths, followed by 2/ lower miocene thrusting. Two Lower Miocene E-W-trending strike-slip corridors played a major role in the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60°-trending thrusts and N140°-trending normal faults developed simultaneously during dextral strike-slip simple shear. The inferred continuous westward translation of the Alboran Domain is accommodated by a major E-W-trending lateral ramp (strike-slip) and a N60°-trending frontal thrust. At lithosphere-scale, we interpret the observed deformation pattern as the upper-plate expression of a lateral slab tear and of its westward propagation since Lower Miocene. The crustal emplacement of the Ronda Peridotites occurred at the onset of this westward motion.The Miocene tectonics of the western Alboran is therefore marked by the inversion of a continental rift, triggered by shortening of the upper continental plate and accommodated by E-W dextral strike-slip corridors. During thrusting and westward displacement of the Alboran domain with respect to Iberia, the hot upper plate, which involved the previously exhumed sub-continental mantle, underwent fast cooling.

Neogene evolution of the North New Guinea basin, Papua New Guinea: New constraints from seismic and subsidence analysis and implications for hydrocarbon exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullen, A.B.; Pigott, J.D.

1990-06-01

The present-day North New Guinea basin is a Plio-Pleistocene successor basin that formed subsequent to accretion of the Finisterre volcanic arc to the Australian Plate. The Ramu, Sepik, and Piore infrabasins formed in a forearc setting relative to the continental Maramuni magmatic arc. The evolution of these infrabasins was strongly influenced by accretion of the composite Torricelli-Prince Alexander terrane to the Australian Plate. Regional reflection seismic data and tectonic subsidence-subsidence rate calculations for seven wells drilled in the North New Guinea basin reveal a complex history. The timing and magnitude of subsidence and changes in subsidence rates differ between eachmore » of the Miocene infrabasins. A diachronous middle to late Miocene unconformity generally truncates infrabasin sequences. The Nopan No. 1 in the Sepik basin, however, has a complete middle Miocene to Pleistocene sedimentary record. This well records late Miocene negative subsidence rates documenting that the Nopan anticline grew as erosion occurred elsewhere in the region. This circumstance suggests that the major, sequence-bounding unconformity results from regional uplift and deformation, rather than changes in global sea level. The Plio-Pleistocene evolution of the North New Guinea basin has two profound implications regarding hydrocarbon exploration. First, the late Pliocene structural inversion of parts of the basin hinders stratigraphic and facies correlation inferred from the present setting. The recognition of basin inversion is particularly important in the Piore basin for predicting the distribution of potential reservoir facies in the Miocene carbonates. Second, the subsidence data suggest that although potential source rocks may be thermally within the oil window, these rocks may not have had sufficient time to mature owing to their recent burial.« less

Stratigraphic units overlying the Zambales Ophiolite Complex (ZOC) in Luzon, (Philippines): Tectonostratigraphic significance and regional implications

NASA Astrophysics Data System (ADS)

Queaño, Karlo L.; Dimalanta, Carla B.; Yumul, Graciano P.; Marquez, Edanjarlo J.; Faustino-Eslava, Decibel V.; Suzuki, Shigeyuki; Ishida, Keisuke

2017-07-01

The Zambales Ophiolite Complex (ZOC) on the island of Luzon, Philippines is one of the most well-studied crust-mantle sequences in the region. Several massifs comprise the ZOC, one of which is the Coto Block overlain by clastic sedimentary units previously dated as Eocene. Geochronologic studies from diabase, granodiorites and other late-stage magmatic products similarly yielded the same age. Succeeding tectonic models have therefore all been grounded on the assumption that the entire ZOC is Eocene. Recent investigations, however, revealed the presence of chert blocks within the Early to Middle Miocene clastic formation overlying the Acoje Block in the northern part of the ophiolite complex. Radiolarians extracted from the cherts yielded a stratigraphic range that suggests a Late Jurassic to Early Cretaceous age. The recognition of a much older age than previously reported of the ZOC warrants a re-examination of its actual distribution and genesis. Correlating with other similarly-aged ophiolites, we suggest defining a western Mesozoic ophiolite belt, largely extending from the west-central portion of the archipelago to the northeastern tip of Luzon island. Tentatively, we attribute the Mesozoic ophiolitic and associated rocks in western Luzon to an arc-continent collision involving the Philippine Mobile Belt and the Palawan Microcontinental Block. In addition, differences in the clastic compositions of the Cenozoic sedimentary formations provide material not only for deciphering the ZOC's unroofing history but also for constraining the timing of province linkage. The intermittent appearance of lithic fragments and detrital minerals from the ophiolite in the units of the Middle Miocene Candelaria Limestone and the Late Miocene to Early Pliocene Sta. Cruz Formation indicates significant but geographically variable contributions from the ophiolite complex. In the northern Zambales Range, the Sta. Cruz Formation caps the Coto Block and the Acoje Block of the ZOC, providing a minimum age for their amalgamation.

East African Cenozoic vegetation history.

PubMed

Linder, Hans Peter

2017-11-01

The modern vegetation of East Africa is a complex mosaic of rainforest patches; small islands of tropic-alpine vegetation; extensive savannas, ranging from almost pure grassland to wooded savannas; thickets; and montane grassland and forest. Here I trace the evolution of these vegetation types through the Cenozoic. Paleogene East Africa was most likely geomorphologically subdued and, as the few Eocene fossil sites suggest, a woodland in a seasonal climate. Woodland rather than rainforest may well have been the regional vegetation. Mountain building started with the Oligocene trap lava flows in Ethiopia, on which rainforest developed, with little evidence of grass and none of montane forests. The uplift of the East African Plateau took place during the middle Miocene. Fossil sites indicate the presence of rainforest, montane forest and thicket, and wooded grassland, often in close juxtaposition, from 17 to 10 Ma. By 10 Ma, marine deposits indicate extensive grassland in the region and isotope analysis indicates that this was a C 3 grassland. In the later Miocene rifting, first of the western Albertine Rift and then of the eastern Gregory Rift, added to the complexity of the environment. The building of the high strato-volcanos during the later Mio-Pliocene added environments suitable for tropic-alpine vegetation. During this time, the C 3 grassland was replaced by C 4 savannas, although overall the extent of grassland was reduced from the mid-Miocene high to the current low level. Lake-level fluctuations during the Quaternary indicate substantial variation in rainfall, presumably as a result of movements in the intertropical convergence zone and the Congo air boundary, but the impact of these fluctuations on the vegetation is still speculative. I argue that, overall, there was an increase in the complexity of East African vegetation complexity during the Neogene, largely as a result of orogeny. The impact of Quaternary climatic fluctuation is still poorly understood. © 2017 Wiley Periodicals, Inc.

Symbiotic Dinoflagellate Functional Diversity Mediates Coral Survival under Ecological Crisis.

PubMed

Suggett, David J; Warner, Mark E; Leggat, William

2017-10-01

Coral reefs have entered an era of 'ecological crisis' as climate change drives catastrophic reef loss worldwide. Coral growth and stress susceptibility are regulated by their endosymbiotic dinoflagellates (genus Symbiodinium). The phylogenetic diversity of Symbiodinium frequently corresponds to patterns of coral health and survival, but knowledge of functional diversity is ultimately necessary to reconcile broader ecological success over space and time. We explore here functional traits underpinning the complex biology of Symbiodinium that spans free-living algae to coral endosymbionts. In doing so we propose a mechanistic framework integrating the primary traits of resource acquisition and utilisation as a means to explain Symbiodinium functional diversity and to resolve the role of Symbiodinium in driving the stability of coral reefs under an uncertain future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Petrologic evolution of divergent peralkaline magmas from the Silent Canyon caldera complex, southwestern Nevada volcanic field

USGS Publications Warehouse

Sawyer, D.A.; Sargent, K.A.

1989-01-01

The Silent Canyon volcanic center consists of a buried Miocene peralkaline caldera complex and outlying peralkaline lava domes. Two widespread ash flow sheets, the Tub Spring and overlying Grouse Canyon members of the Miocene Belted Range Tuff, were erupted from the caldera complex and have volumes of 60-100 km3 and 200 km3, respectively. Eruption of the ash flows was preceded by widespread extrusion of precaldera comendite domes and was followed by extrusion of postcollapse peralkaline lavas and tuffs within and outside the caldera complex. Lava flows and tuffs were also deposited between the two major ash flow sheets. Rocks of the Silent Canyon center vary significantly in silica content and peralkalinity. Weakly peralkaline silicic comendites (PI 1.0-1.1) are the most abundant precaldera lavas. Postcollapse lavas range from trachyte to silicic comendite; some have anomalous light rare earth element (LREE) enrichments. Silent Canyon rocks follow a common petrologic evolution from trachyte to low-silica comendite; above 73% SiO2, compositions of the moderately peralkaline comendites diverge from those of the weakly peralkaline silicic comendites. The development of divergent peralkaline magmas, toward both pantelleritic and weakly peralkaline compositions, is unusual in a single volcanic center. -from Authors

New constrains on the thermal history of the Miocene Jarando basin (Southern Serbia)

NASA Astrophysics Data System (ADS)

Andrić, Nevena; Životić, Dragana; Fügenschuh, Bernhard; Cvetković, Vladica

2013-04-01

The Jarando basin, located in the internal Dinarides, formed in the course of the Miocene extension affecting the whole Alpine-Carpathian-Dinaride system (Schmid et al., 2008). In the study area Miocene extension led to the formation of a core-complex in the Kopaonik area (Schefer et al., 2011) with the Jarando basin located in the hanging wall of the detachment fault. The Jarando basin is characterized by the presence of bituminous coals, whereas in the other intramontane basins in Serbia coalification did not exceed the subbituminous stage within the same stratigraphic level. Furthermore, the basin hosts boron mineralizations (borates and howlite) and a magnesite deposit, which again implies elevated temperatures. This thermal overprint is possibly due to post-magmatic activity related to the emplacement of Oligocene I-type Kopaonik and Miocene S-type Polumir granitoid (Schefer et al., 2011.). This research project is aimed at providing new information about the thermal history of the Jarando basin. Fifteen core samples from three boreholes and 10 samples from the surrounding outcrops were processed for apatite fission-track analysis. Additionally, vitrinite reflectance was measured for 11 core samples of shales from one borehole and 5 samples of coal from an underground mine. VR data of Early to Middle Miocene sediments reveal a strong post-depositional overprint. Values increase with the depth from 0.66-0.79% to 0.83-0.90%. Thus organic matter reached the bituminous stage and experienced temperatures of around 110-120˚C (Barker and Pawlewicz, 1994). FT single grain ages for apatite scatter between 45 Ma to 10 Ma with a general trend towards younger ages with depth. Both, the spread in single grain ages together with the bimodal track lengths distribution clearly point to partial annealing of the detrital apatites. With the temperature given from the VR values the partial annealing points to a rather short-lived thermal event. This is assisted by thermal modelling of our fission track data indicating that maximum temperatures of <120°C around 15-12 Ma. We correlate the thermal event with the extension and core-complex formation followed by the syn-extensional intrusion of the Polumir granite. Later cooling from 10 Ma onwards is related to basin inversion and erosion.

Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia)

PubMed Central

2015-01-01

Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs is consistent with the disturbance-mosaic (microhabitat heterogeneity) hypothesis. Calculations of the FORAM Index (FI), a single metric index to assess reef vitality, indicate that all fore- and most back-reef environments support active carbonate accretion and provide habitat suitability for carbonate producers dependent on algal symbiosis. Lowest suitability values were recorded within the innermost bays, an area where natural and increasing anthropogenic influences continue to impact the reefs. The presence of habitat specific assemblages and numerical abundance values of individual taxa show that benthic foraminifera are excellent recorders of environmental perturbations and good indicators useful in modern and ancient ecological and environmental studies. PMID:26710320

Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia).

PubMed

Fajemila, Olugbenga T; Langer, Martin R; Lipps, Jere H

2015-01-01

Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs is consistent with the disturbance-mosaic (microhabitat heterogeneity) hypothesis. Calculations of the FORAM Index (FI), a single metric index to assess reef vitality, indicate that all fore- and most back-reef environments support active carbonate accretion and provide habitat suitability for carbonate producers dependent on algal symbiosis. Lowest suitability values were recorded within the innermost bays, an area where natural and increasing anthropogenic influences continue to impact the reefs. The presence of habitat specific assemblages and numerical abundance values of individual taxa show that benthic foraminifera are excellent recorders of environmental perturbations and good indicators useful in modern and ancient ecological and environmental studies.

Larval Settlement: The Role of Surface Topography for Sessile Coral Reef Invertebrates

PubMed Central

Whalan, Steve; Abdul Wahab, Muhammad A.; Sprungala, Susanne; Poole, Andrew J.; de Nys, Rocky

2015-01-01

For sessile marine invertebrates with complex life cycles, habitat choice is directed by the larval phase. Defining which habitat-linked cues are implicated in sessile invertebrate larval settlement has largely concentrated on chemical cues which are thought to signal optimal habitat. There has been less effort establishing physical settlement cues, including the role of surface microtopography. This laboratory based study tested whether surface microtopography alone (without chemical cues) plays an important contributing role in the settlement of larvae of coral reef sessile invertebrates. We measured settlement to tiles, engineered with surface microtopography (holes) that closely matched the sizes (width) of larvae of a range of corals and sponges, in addition to surfaces with holes that were markedly larger than larvae. Larvae from two species of scleractinian corals (Acropora millepora and Ctenactis crassa) and three species of coral reef sponges (Luffariella variabilis, Carteriospongia foliascens and Ircinia sp.,) were used in experiments. L. variabilis, A. millepora and C. crassa showed markedly higher settlement to surface microtopography that closely matched their larval width. C. foliascens and Ircinia sp., showed no specificity to surface microtopography, settling just as often to microtopography as to flat surfaces. The findings of this study question the sole reliance on chemical based larval settlement cues, previously established for some coral and sponge species, and demonstrate that specific physical cues (surface complexity) can also play an important role in larval settlement of coral reef sessile invertebrates. PMID:25671562

Larval settlement: the role of surface topography for sessile coral reef invertebrates.

PubMed

Whalan, Steve; Wahab, Muhammad A Abdul; Sprungala, Susanne; Poole, Andrew J; de Nys, Rocky

2015-01-01

For sessile marine invertebrates with complex life cycles, habitat choice is directed by the larval phase. Defining which habitat-linked cues are implicated in sessile invertebrate larval settlement has largely concentrated on chemical cues which are thought to signal optimal habitat. There has been less effort establishing physical settlement cues, including the role of surface microtopography. This laboratory based study tested whether surface microtopography alone (without chemical cues) plays an important contributing role in the settlement of larvae of coral reef sessile invertebrates. We measured settlement to tiles, engineered with surface microtopography (holes) that closely matched the sizes (width) of larvae of a range of corals and sponges, in addition to surfaces with holes that were markedly larger than larvae. Larvae from two species of scleractinian corals (Acropora millepora and Ctenactis crassa) and three species of coral reef sponges (Luffariella variabilis, Carteriospongia foliascens and Ircinia sp.,) were used in experiments. L. variabilis, A. millepora and C. crassa showed markedly higher settlement to surface microtopography that closely matched their larval width. C. foliascens and Ircinia sp., showed no specificity to surface microtopography, settling just as often to microtopography as to flat surfaces. The findings of this study question the sole reliance on chemical based larval settlement cues, previously established for some coral and sponge species, and demonstrate that specific physical cues (surface complexity) can also play an important role in larval settlement of coral reef sessile invertebrates.

Territorial user rights for fisheries as ancillary instruments for marine coastal conservation in Chile.

PubMed

Gelcich, Stefan; Fernández, Miriam; Godoy, Natalio; Canepa, Antonio; Prado, Luis; Castilla, Juan Carlos

2012-12-01

Territorial user rights for fisheries have been advocated as a way to achieve sustainable resource management. However, few researchers have empirically assessed their potential as ancillary marine conservation instruments by comparing them to no-take marine protected areas. In kelp (Lessonia trabeculata) forests of central Chile, we compared species richness, density, and biomass of macroinvertebrates and reef fishes among territorial-user-right areas with low-level and high-level enforcement, no-take marine protected areas, and open-access areas in 42 100-m subtidal transects. We also assessed structural complexity of the kelp forest and substratum composition. Multivariate randomized permutation tests indicated macroinvertebrate and reef fish communities associated with the different access regimes differed significantly. Substratum composition and structural complexity of kelp forest did not differ among access regimes. Univariate analyses showed species richness, biomass, and density of macroinvertebrates and reef fishes were greater in highly enforced territorial-user-right areas and no-take marine protected areas than in open-access areas. Densities of macroinvertebrates and reef fishes of economic importance were not significantly different between highly enforced territorial-user-right and no-take marine protected areas. Densities of economically important macroinvertebrates in areas with low-level enforcement were significantly lower than those in areas with high-level enforcement and no-take marine protected areas but were significantly higher than in areas with open access. Territorial-user-right areas could be important ancillary conservation instruments if they are well enforced. ©2012 Society for Conservation Biology.

Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the island of Fuerteventura

NASA Astrophysics Data System (ADS)

Ancochea, E.; Brändle, J. L.; Cubas, C. R.; Hernán, F.; Huertas, M. J.

1996-03-01

Fuerteventura has been since early stages of its growth the result of three different adjacent large volcanic complexes: Southern, Central and Northern. The definition of these volcanic complexes and their respective growing episodes is based on volcano-stratigraphic, morphological and structural criteria, particularly radial dyke swarms. Each complex has its own prolonged history that might be longer than 10 m.y. During that time, several periods of activity alternating with gaps accompanied by important erosion took place. The evolution of each volcanic complex has been partially independent but all the three are affected by at least three Miocene tectonic phases that controlled considerably their activity. The volcanic complexes are deeply eroded and partially submerged. In the core of the Northern and the Central volcanic complexes there is a set of submarine and plutonic rocks intensely traversed by a dyke swarm, known as the Basal Complex. The Basal Complex has been interpreted in different ways but all previous authors have considered it to be prior to the subaerial shield stage of the island. Here we advance the idea that the Basal Complex represent the submarine growing stage of the volcanic complexes and the hypabyssal roots (plutons and dykes) of their successive subaerial growing episodes. Two seamounts situated nearby, southwest of the island, might be interpreted as remains of two other major volcanoes. These two volcanoes, together with those forming the present emerged island of Fuerteventura, and finally those of Famara and Los Ajaches situated further north on Lanzarote constitute a chain of volcanoes located along a lineation which is subparallel to the northwestern African coastline and which may relate to early Atlantic spreading trends in the area.

Circadian clocks in symbiotic corals: the duet between Symbiodinium algae and their coral host.

PubMed

Sorek, Michal; Díaz-Almeyda, Erika M; Medina, Mónica; Levy, Oren

2014-04-01

To date, the association and synchronization between two organismal circadian clocks ticking in parallel as part of a meta-organism (termed a symbiotic association), have rarely been investigated. Reef-building corals exhibit complex rhythmic responses to diurnal, lunar, and annual changes. Understanding circadian, circatidal, and annual regulation in reef-building corals is complicated by the presence of photosynthetic endosymbionts, which have a profound physiochemical influence on the intracellular environment. How corals tune their animal-based clock machinery to respond to external cues while simultaneously responding to internal physiological changes imposed by the symbiont, is not clear. There is insufficient molecular or physiological evidence of the existence of a circadian pacemaker that controls the metabolism, photosynthesis, synchronized mass spawning, and calcification processes in symbiotic corals. In this review, we present current knowledge regarding the animal pacemaker and the symbiotic-algal pacemaker. We examine the evidence from behavioral, physiological, molecular, and evolutionary perspectives. We explain why symbiotic corals are an interesting model with which to study the complexities and evolution of the metazoan circadian clock. We also provide evidence of why the chronobiology of corals is fundamental and extremely important for explaining the biology, physiology, and metabolism of coral reefs. A deeper understanding of these complex issues can help explain coral mass spawning, one of the earth's greatest and most mysterious behavioral phenomena. Copyright © 2014 Elsevier B.V. All rights reserved.

Taxonomic and Functional Metagenomic Signature of Turfs in the Abrolhos Reef System (Brazil)

PubMed Central

Walter, Juline M.; Tschoeke, Diogo A.; Meirelles, Pedro M.; de Oliveira, Louisi; Leomil, Luciana; Tenório, Márcio; Valle, Rogério; Salomon, Paulo S.; Thompson, Cristiane C.; Thompson, Fabiano L.

2016-01-01

Turfs are widespread assemblages (consisting of microbes and algae) that inhabit reef systems. They are the most abundant benthic component in the Abrolhos reef system (Brazil), representing greater than half the coverage of the entire benthic community. Their presence is associated with a reduction in three-dimensional coral reef complexity and decreases the habitats available for reef biodiversity. Despite their importance, the taxonomic and functional diversity of turfs remain unclear. We performed a metagenomics and pigments profile characterization of turfs from the Abrolhos reefs. Turf microbiome primarily encompassed Proteobacteria (mean 40.57% ± s.d. 10.36, N = 1.548,192), Cyanobacteria (mean 35.04% ± s.d. 15.5, N = 1.337,196), and Bacteroidetes (mean 11.12% ± s.d. 4.25, N = 424,185). Oxygenic and anoxygenic phototrophs, chemolithotrophs, and aerobic anoxygenic phototrophic (AANP) bacteria showed a conserved functional trait of the turf microbiomes. Genes associated with oxygenic photosynthesis, AANP, sulfur cycle (S oxidation, and DMSP consumption), and nitrogen metabolism (N2 fixation, ammonia assimilation, dissimilatory nitrate and nitrite ammonification) were found in the turf microbiomes. Principal component analyses of the most abundant taxa and functions showed that turf microbiomes differ from the other major Abrolhos benthic microbiomes (i.e., corals and rhodoliths) and seawater. Taken together, these features suggest that turfs have a homogeneous functional core across the Abrolhos Bank, which holds diverse microbial guilds when comparing with other benthic organisms. PMID:27548380

Early-mid-Cretaceous evolution in Tethyan reef communities and sea level

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, R.W.

1988-01-01

The replacement of corals by rudists in Early Cretaceous reefal communities spanned a 30-m.y. period when sea level rose and drowned continental shelves. During this time corals formed communities in the deeper parts of reefs and rudists occupied the shallow, high-energy habitats. By Aptian time rudists dominated reefs that fringed interior shelf basins and corals formed reefs with rudists on the outer shelf margins. By late Albian coral communities had virtually disappeared, presumably because of complex environmental changes and cycles of organic productivity. Two important events of eustatic sea level rise are represented by unconformities separating carbonate depositional sequences onmore » the Arabian platform that correlate with sequence boundaries on the Gulf Coast platform. Graphic correlation techniques test the synchroneity of these events. A composite standard time scale dates these sea level rises at 115.8 Ma and 94.6 Ma; a third, intra-Albian event at 104.3 Ma is present in many places and may also be eustatic. Associated with these sea level rises were apparent changes in ocean water chemistry as evidenced by changes in isotopes and trace elements, where diagenetic effects can be discounted. During this time the climate became more humid and atmospheric CO/sub 2/ increased. The concomitant environmental changes in the oceanic conditions presumably stressed the deeper coral communities on reefs. The emergence of rudists as reef contributors had a profound effect on Late Cretaceous depositional conditions and the development of hydrocarbon reservoirs.« less

Early-mid-Cretaceous evolution in Tethyan reef communities and sea level

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, R.W.

1988-02-01

The replacement of corals by rudists in Early Cretaceous reefal communities spanned a 30-m.y. period when sea level rose and drowned continental shelves. During this time corals formed communities in the deeper parts of reefs and rudists occupied the shallow, high-energy habitats. By Aptian time rudists dominated reefs that fringed interior shelf basins and corals formed reefs with rudists on the outer shelf margins. By late Albian coral communities had virtually disappeared, presumably because of complex environmental changes and cycles of organic productivity. Two important events of eustatic sea level rise are represented by unconformities separating carbonate depositional sequences onmore » the Arabian platform that correlate with sequence boundaries on the Gulf Coast platform. Graphic correlation techniques test the synchroneity of these events. A composite standard time scale dates these sea level rises at 115.8 Ma and 94.6 Ma; a third, intra-Albian event at 104.3 Ma is present in many places and may also be eustatic. Associated with these sea level rises were apparent changes in ocean water chemistry as evidenced by changes in isotopes and trace elements, where diagenetic effects can be discounted. During this time the climate became more humid and atmospheric CO/sub 2/ increased. The concomitant environmental changes in the oceanic conditions presumably stressed the deeper coral communities on reefs. The emergence of rudists as reef contributors had a profound effect on Late Cretaceous depositional conditions and the development of hydrocarbon reservoirs.« less

The "Flexi-Chamber": A Novel Cost-Effective In Situ Respirometry Chamber for Coral Physiological Measurements.

PubMed

Camp, Emma F; Krause, Sophie-Louise; Santos, Lourianne M F; Naumann, Malik S; Kikuchi, Ruy K P; Smith, David J; Wild, Christian; Suggett, David J

2015-01-01

Coral reefs are threatened worldwide, with environmental stressors increasingly affecting the ability of reef-building corals to sustain growth from calcification (G), photosynthesis (P) and respiration (R). These processes support the foundation of coral reefs by directly influencing biogeochemical nutrient cycles and complex ecological interactions and therefore represent key knowledge required for effective reef management. However, metabolic rates are not trivial to quantify and typically rely on the use of cumbersome in situ respirometry chambers and/or the need to remove material and examine ex situ, thereby fundamentally limiting the scale, resolution and possibly the accuracy of the rate data. Here we describe a novel low-cost in situ respirometry bag that mitigates many constraints of traditional glass and plexi-glass incubation chambers. We subsequently demonstrate the effectiveness of our novel "Flexi-Chamber" approach via two case studies: 1) the Flexi-Chamber provides values of P, R and G for the reef-building coral Siderastrea cf. stellata collected from reefs close to Salvador, Brazil, which were statistically similar to values collected from a traditional glass respirometry vessel; and 2) wide-scale application of obtaining P, R and G rates for different species across different habitats to obtain inter- and intra-species differences. Our novel cost-effective design allows us to increase sampling scale of metabolic rate measurements in situ without the need for destructive sampling and thus significantly expands on existing research potential, not only for corals as we have demonstrated here, but also other important benthic groups.

Early evidence for complex social structure in Proboscidea from a late Miocene trackway site in the United Arab Emirates

PubMed Central

Bibi, Faysal; Kraatz, Brian; Craig, Nathan; Beech, Mark; Schuster, Mathieu; Hill, Andrew

2012-01-01

Many living vertebrates exhibit complex social structures, evidence for the antiquity of which is limited to rare and exceptional fossil finds. Living elephants possess a characteristic social structure that is sex-segregated and multi-tiered, centred around a matriarchal family and solitary or loosely associated groups of adult males. Although the fossil record of Proboscidea is extensive, the origin and evolution of social structure in this clade is virtually unknown. Here, we present imagery and analyses of an extensive late Miocene fossil trackway site from the United Arab Emirates. The site of Mleisa 1 preserves exceptionally long trackways of a herd of at least 13 individuals of varying size transected by that of a single large individual, indicating the presence of both herding and solitary social modes. Trackway stride lengths and resulting body mass estimates indicate that the solitary individual was also the largest and therefore most likely a male. Sexual determination for the herd is equivocal, but the body size profile and number of individuals are commensurate with those of a modern elephant family unit. The Mleisa 1 trackways provide direct evidence for the antiquity of characteristic and complex social structure in Proboscidea. PMID:22357934

Bacterial communities associated with three Brazilian endemic reef corals (Mussismilia spp.) in a coastal reef of the Abrolhos shelf

NASA Astrophysics Data System (ADS)

de Castro, Alinne Pereira; Araújo, Samuel Dias; Reis, Alessandra M. M.; Pompeu, Maira; Hatay, Mark; de Moura, Rodrigo Leão; Francini-Filho, Ronaldo B.; Thompson, Fabiano L.; Krüger, Ricardo H.

2013-11-01

The diversity of bacterial communities associated with three Brazilian endemic reef corals from genus Mussismilia (M. hispida, M. braziliensis, and M. harttii) at a single site was assessed using 16S rRNA clone libraries. The study site, Pedra do Leste, is a coastal reef within the largest and richest South Atlantic coralline reef complex (Abrolhos Bank) and is subject to high fishing pressure, high sedimentation loads, and other land-based stressors. The three coral species are Neogene relicts with unique biological and morphological traits that enable them to survive relatively high sedimentation levels. Our results show that sequences affiliated with γ-Proteobacteria predominated, accounting for more than 60% of the examined sequences. Indeed, the most frequent species were related to Alteromonas, Marinomonas, Neptuniibacter, and Vibrio, which are copiotrophic microorganisms common in environments highly affected by anthropogenic stress. Principal component analysis revealed that bacterial communities of M. braziliensis and M. hispida were more similar to each other than to M. harttii-associated bacteria. Such pattern is likely related to distinct morphological properties of M. harttii, such as the existence of phaceloid colonies, in which polyps are not connected by soft tissue. This is the first investigation assessing the bacterial communities of the three Brazilian endemic Mussismilia species at the same location.

A unified framework for modelling sediment fate from source to sink and its interactions with reef systems over geological times.

PubMed

Salles, Tristan; Ding, Xuesong; Webster, Jody M; Vila-Concejo, Ana; Brocard, Gilles; Pall, Jodie

2018-03-27

Understanding the effects of climatic variability on sediment dynamics is hindered by limited ability of current models to simulate long-term evolution of sediment transfer from source to sink and associated morphological changes. We present a new approach based on a reduced-complexity model which computes over geological time: sediment transport from landmasses to coasts, reworking of marine sediments by longshore currents, and development of coral reef systems. Our framework links together the main sedimentary processes driving mixed siliciclastic-carbonate system dynamics. It offers a methodology for objective and quantitative sediment fate estimations over regional and millennial time-scales. A simulation of the Holocene evolution of the Great Barrier Reef shows: (1) how high sediment loads from catchments erosion prevented coral growth during the early transgression phase and favoured sediment gravity-flows in the deepest parts of the northern region basin floor (prior to 8 ka before present (BP)); (2) how the fine balance between climate, sea-level, and margin physiography enabled coral reefs to thrive under limited shelf sedimentation rates after ~6 ka BP; and, (3) how since 3 ka BP, with the decrease of accommodation space, reduced of vertical growth led to the lateral extension of reefs consistent with available observational data.

Ocean Transport Pathways to a World Heritage Fringing Coral Reef: Ningaloo Reef, Western Australia.

PubMed

Xu, Jiangtao; Lowe, Ryan J; Ivey, Gregory N; Jones, Nicole L; Zhang, Zhenlin

2016-01-01

A Lagrangian particle tracking model driven by a regional ocean circulation model was used to investigate the seasonally varying connectivity patterns within the shelf circulation surrounding the 300 km long Ningaloo Reef in Western Australia (WA) during 2009-2010. Forward-in-time simulations revealed that surface water was transported equatorward and offshore in summer due to the upwelling-favorable winds. In winter, however, water was transported polewards down the WA coast due to the seasonally strong Leeuwin Current. Using backward-in-time simulations, the subsurface transport pathways revealed two main source regions of shelf water reaching Ningaloo Reef: (1) a year-round source to the northeast in the upper 100 m of water column; and (2) during the summer, an additional source offshore and to the west of Ningaloo in depths between ~30 and ~150 m. Transient wind-driven coastal upwelling, onshore geostrophic transport and stirring by offshore eddies were identified as the important mechanisms influencing the source water origins. The identification of these highly time-dependent transport pathways and source water locations is an essential step towards quantifying how key material (e.g., nutrients, larvae, contaminants, etc.) is exchanged between Ningaloo Reef and the surrounding shelf ocean, and how this is mechanistically coupled to the complex ocean dynamics in this region.

A model-based approach to determine the long-term effects of multiple interacting stressors on coral reefs.

PubMed

Blackwood, Julie C; Hastings, Alan; Mumby, Peter J

2011-10-01

The interaction between multiple stressors on Caribbean coral reefs, namely, fishing effort and hurricane impacts, is a key element in the future sustainability of reefs. We develop an analytic model of coral-algal interactions and explicitly consider grazing by herbivorous reef fish. Further, we consider changes in structural complexity, or rugosity, in addition to the direct impacts of hurricanes, which are implemented as stochastic jump processes. The model simulations consider various levels of fishing effort corresponding to' several hurricane frequencies and impact levels dependent on geographic location. We focus on relatively short time scales so we do not explicitly include changes in ocean temperature, chemistry, or sea level rise. The general features of our approach would, however, apply to these other stressors and to the management of other systems in the face of multiple stressors. It is determined that the appropriate management policy, either local reef restoration or fisheries management, greatly depends on hurricane frequency and impact level. For sufficiently low hurricane impact and macroalgal growth rate, our results indicate that regions with lower-frequency hurricanes require stricter fishing regulations, whereas management in regions with higher-frequency hurricanes might be less concerned with enhancing grazing and instead consider whether local-scale restorative activities to increase vertical structure are cost-effective.

Ocean Transport Pathways to a World Heritage Fringing Coral Reef: Ningaloo Reef, Western Australia

PubMed Central

Xu, Jiangtao; Lowe, Ryan J.; Ivey, Gregory N.; Jones, Nicole L.; Zhang, Zhenlin

2016-01-01

A Lagrangian particle tracking model driven by a regional ocean circulation model was used to investigate the seasonally varying connectivity patterns within the shelf circulation surrounding the 300 km long Ningaloo Reef in Western Australia (WA) during 2009–2010. Forward-in-time simulations revealed that surface water was transported equatorward and offshore in summer due to the upwelling-favorable winds. In winter, however, water was transported polewards down the WA coast due to the seasonally strong Leeuwin Current. Using backward-in-time simulations, the subsurface transport pathways revealed two main source regions of shelf water reaching Ningaloo Reef: (1) a year-round source to the northeast in the upper 100 m of water column; and (2) during the summer, an additional source offshore and to the west of Ningaloo in depths between ~30 and ~150 m. Transient wind-driven coastal upwelling, onshore geostrophic transport and stirring by offshore eddies were identified as the important mechanisms influencing the source water origins. The identification of these highly time-dependent transport pathways and source water locations is an essential step towards quantifying how key material (e.g., nutrients, larvae, contaminants, etc.) is exchanged between Ningaloo Reef and the surrounding shelf ocean, and how this is mechanistically coupled to the complex ocean dynamics in this region. PMID:26790154

Extended geographic distribution of several Indo-Pacific coral reef diseases.

PubMed

Weil, E; Irikawa, A; Casareto, B; Suzuki, Y

2012-03-20

Other than coral bleaching, few coral diseases or diseases of other reef organisms have been reported from Japan. This is the first report of lesions similar to Porites ulcerative white spots (PUWS), brown band disease (BrB), pigmentation response (PR), and crustose coralline white syndrome (CCWS) for this region. To assess the health status and disease prevalence, qualitative and quantitative surveys (3 belt transects of 100 m² each on each reef) were performed in March and September 2010 on 2 reefs of the Ginowan-Ooyama reef complex off Okinawa, and 2 protected reefs off Zamani Island, in the Kerama Islands 40 km west of Okinawa. Overall, mean (±SD) disease prevalence was higher in Ginowan-Ooyama (9.7 ± 7.9%) compared to Zamami (3.6 ± 4.6%). Porites lutea was most affected by PUWS at Ooyama (23.1 ± 10.4 vs. 4.5 ± 5.2%). White syndrome (WS) mostly affected Acropora cytherea (12. 5 ± 18.0%) in Zamami and Oxipora lacera (10.2 ± 10%) in Ooyama. Growth anomalies (GA) and BrB were only observed on A. cytherea (8.3 ± 6.2%) and A. nobilis (0.8%) at Zamami. Black band disease affected Pachyseris speciosa (6.0 ± 4.6%) in Ooyama only. Pigmentation responses (PR) were common in massive Porites in both localities (2.6 ± 1.9 and 5.6 ± 2.3% respectively). Crustose coralline white syndrome (CCWS) was observed in both localities. These results significantly expand the geographic distribution of PUWS, BrB, PR and CCWS in the Indo-Pacific, indicating that the northernmost coral reefs in the western Pacific are susceptible to a larger number of coral diseases than previously thought.

Consequences of ecological, evolutionary and biogeochemical uncertainty for coral reef responses to climatic stress.

PubMed

Mumby, Peter J; van Woesik, Robert

2014-05-19

Coral reefs are highly sensitive to the stress associated with greenhouse gas emissions, in particular ocean warming and acidification. While experiments show negative responses of most reef organisms to ocean warming, some autotrophs benefit from ocean acidification. Yet, we are uncertain of the response of coral reefs as systems. We begin by reviewing sources of uncertainty and complexity including the translation of physiological effects into demographic processes, indirect ecological interactions among species, the ability of coral reefs to modify their own chemistry, adaptation and trans-generational plasticity. We then incorporate these uncertainties into two simple qualitative models of a coral reef system under climate change. Some sources of uncertainty are far more problematic than others. Climate change is predicted to have an unambiguous negative effect on corals that is robust to several sources of uncertainty but sensitive to the degree of biogeochemical coupling between benthos and seawater. Macroalgal, zoanthid, and herbivorous fish populations are generally predicted to increase, but the ambiguity (confidence) of such predictions are sensitive to the source of uncertainty. For example, reversing the effect of climate-related stress on macroalgae from being positive to negative had no influence on system behaviour. By contrast, the system was highly sensitive to a change in the stress upon herbivorous fishes. Minor changes in competitive interactions had profound impacts on system behaviour, implying that the outcomes of mesocosm studies could be highly sensitive to the choice of taxa. We use our analysis to identify new hypotheses and suggest that the effects of climatic stress on coral reefs provide an exceptional opportunity to test emerging theories of ecological inheritance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Observations of turbulent mixing in a shallow coral reef

NASA Astrophysics Data System (ADS)

Huang, Z. C.

2016-02-01

In situ measurements of waves, currents, and turbulence are presented to study turbulence properties within a depression that is surrounded by multiple coral-reef colonies in a fringing reef in Hobihu, Nan-Wan Bay, southern Taiwan. Turbulence was measured using a dual velocimetry technique, and wave bias contamination in the turbulence is controlled using ogive curve testing of the turbulent shear stress. The observed turbulent dissipation rate is approximately five times greater than simultaneous observations over the nearby sandy bottom site, which indicates stronger mixing within the coral reef than on sandy bottoms. Energetic downward momentum flux exists due to sweeping process; the turbulent kinetic energy is transported downward into the depression through the mechanisms of vertical turbulent transport and advection. The observed turbulent dissipation rate exceeds the shear production rate, which suggests that transport terms or other source terms might be important. The wake flow caused by the resistance force of coral colonies is examined. The form drag coefficient was estimated from the time-averaged alongshore linear momentum between two sites upstream and within the coral reef. The work done due to the form drag, which is termed the wake production, is found to strongly correlate and approximate well to the observed turbulent dissipation rate. The effects of waves and currents on the wake production are discussed. The observed TSS can be described well by classic turbulence closure model when the empirical stability function is adjusted. This study suggests that the complex canopy structure of multiple colonies and the coexistence of the wave-induced and current flows are significant factors for energetic turbulence in the coral reef, which could have positive effects to the health of the coral reefs.

Selective predation for low body condition at the larval-juvenile transition of a coral reef fish.

PubMed

Hoey, Andrew S; McCormick, Mark I

2004-03-01

Mortality is known to be high during the transition from larval to juvenile life stages in organisms that have complex life histories. We are only just beginning to understand the processes that influence which individuals survive this period of high mortality, and which traits may be beneficial. Here we document a field experiment that examines the selectivity of predation immediately following settlement to the juvenile population in a common tropical fish, Pomacentrus amboinensis (Pomacentridae). Newly metamorphosed fish were tagged and randomly placed onto replicated patches of natural habitat cleared of resident fishes. After exposure to transient predators for 3 days, fish were recollected and the attributes of survivors from patch reefs that sustained high mortality were compared to individuals from patch reefs that experienced low mortality. Seven characteristics of individuals, which were indicative of previous and present body condition, were compared between groups. Predation was found to be selective for fish that grew slowly in the latter third of their larval phase, were low in total lipids, and had a high standardized weight (Fulton's K). Traits developed in the larval phase can strongly influence the survival of individuals over this critical transition period for organisms with complex life cycles.

Remote sensing of deep hermatypic coral reefs in Puerto Rico and the U.S. Virgin Islands using the Seabed autonomous underwater vehicle

NASA Astrophysics Data System (ADS)

Armstrong, Roy A.; Singh, Hanumant

2006-09-01

Optical imaging of coral reefs and other benthic communities present below one attenuation depth, the limit of effective airborne and satellite remote sensing, requires the use of in situ platforms such as autonomous underwater vehicles (AUVs). The Seabed AUV, which was designed for high-resolution underwater optical and acoustic imaging, was used to characterize several deep insular shelf reefs of Puerto Rico and the US Virgin Islands using digital imagery. The digital photo transects obtained by the Seabed AUV provided quantitative data on living coral, sponge, gorgonian, and macroalgal cover as well as coral species richness and diversity. Rugosity, an index of structural complexity, was derived from the pencil-beam acoustic data. The AUV benthic assessments could provide the required information for selecting unique areas of high coral cover, biodiversity and structural complexity for habitat protection and ecosystem-based management. Data from Seabed sensors and related imaging technologies are being used to conduct multi-beam sonar surveys, 3-D image reconstruction from a single camera, photo mosaicking, image based navigation, and multi-sensor fusion of acoustic and optical data.

Fish-derived nutrient hotspots shape coral reef benthic communities.

PubMed

Shantz, Andrew A; Ladd, Mark C; Schrack, Elizabeth; Burkepile, Deron E

2015-12-01

Animal-derived nutrients play an important role in structuring nutrient regimes within and between ecosystems. When animals undergo repetitive, aggregating behavior through time, they can create nutrient hotspots where rates of biogeochemical activity are higher than those found in the surrounding environment. In turn, these hotspots can influence ecosystem processes and community structure. We examined the potential for reef fishes from the family Haemulidae (grunts) to create nutrient hotspots and the potential impact of these hotspots on reef communities. To do so, we tracked the schooling locations of diurnally migrating grunts, which shelter at reef sites during the day but forage off reef each night, and measured the impact of these fish schools on benthic communities. We found that grunt schools showed a high degree of site fidelity, repeatedly returning to the same coral heads. These aggregations created nutrient hotspots around coral heads where nitrogen and phosphorus delivery was roughly 10 and 7 times the respective rates of delivery to structurally similar sites that lacked schools of these fishes. In turn, grazing rates of herbivorous fishes at grunt-derived hotspots were approximately 3 times those of sites where grunts were rare. These differences in nutrient delivery and grazing led to distinct benthic communities with higher cover of crustose coralline algae and less total algal abundance at grunt aggregation sites. Importantly, coral growth was roughly 1.5 times greater at grunt hotspots, likely due to the important nutrient subsidy. Our results suggest that schooling reef fish and their nutrient subsidies play an important role in mediating community structure on coral reefs and that overfishing may have important negative consequences on ecosystem functions. As such, management strategies must consider mesopredatory fishes in addition to current protection often offered to herbivores and top-tier predators. Furthermore, our results suggest that restoration strategies may benefit from focusing on providing structure for aggregating fishes on reefs with low topographic complexity or focusing the restoration of nursery raised corals around existing nutrient hotspots.

Episodic Disturbance from Boat Anchoring Is a Major Contributor to, but Does Not Alter the Trajectory of, Long-Term Coral Reef Decline.

PubMed

Forrester, Graham E; Flynn, Rebecca L; Forrester, Linda M; Jarecki, Lianna L

2015-01-01

Isolating the relative effects of episodic disturbances and chronic stressors on long-term community change is challenging. We assessed the impact of an episodic disturbance associated with human visitation (boat anchoring) relative to other drivers of long-term change on coral reefs. A one-time anchoring event at Crab Cove, British Virgin Islands, in 2004 caused rapid losses of coral and reef structural complexity that were equal to the cumulative decline over 23 years observed at an adjacent site. The abundance of small site-attached reef fishes dropped by approximately one quarter after the anchoring event, but this drop was not immediate and only fully apparent two years after the anchoring event. There was no obvious recovery from the impact, and no evidence that this episodic impact accelerated or retarded subsequent declines from other causes. This apparent lack of synergism between the effect of this episodic human impact and other chronic stressors is consistent with the few other long-term studies of episodic impacts, and suggests that action to mitigate anchor damage should yield predictable benefits.

Late Cretaceous Localized Crustal Thickening as a Primary Control on the 3-D Architecture and Exhumation Histories of Cordilleran Metamorphic Core Complexes

NASA Astrophysics Data System (ADS)

Gans, P. B.; Wong, M.

2014-12-01

The juxtaposition of mylonitic mid-crustal rocks and faulted supracrustal rocks in metamorphic core complexes (MMCs) is usually portrayed in 2 dimensions and attributed to a single event of large-scale slip ± isostatic doming along a low-angle "detachment fault"/ shear zone. This paradigm does not explain dramatic along strike (3-D) variations in slip magnitude, footwall architecture, and burial / exhumation histories of most MMCs. A fundamental question posed by MMCs is how did their earlier thickening and exhumation histories influence the geometric evolution and 3-D slip distribution on the subsequent detachment faults? New geologic mapping and 40Ar/39Ar thermochronology from the Snake Range-Kern Mts-Deep Creek Mts (SKDC) complex in eastern Nevada offer important insights into this question. Crustal shortening and thickening by large-scale non-cylindrical recumbent folds and associated thrust faults during the late Cretaceous (90-80 Ma) resulted in deep burial (650°C, 20-25 km) of the central part of the footwall, but metamorphic grade decreases dramatically to the N and S in concert with decreasing amplitude on the shortening structures. Subsequent Paleogene extensional exhumation by normal faulting and ESE-directed mylonitic shearing is greatest in areas of maximum earlier thickening and brought highest grade rocks back to depths of~10-12 km. After ≥15 Ma of quiescence, rapid E-directed slip initiated along the brittle Miocene Snake Range detachment at 20 Ma and reactivated the Eocene shear zone. The ≥200°C gradient across the footwall at this time implies that the Miocene slip surface originated as a moderately E-dipping normal fault. This Miocene slip surface can be tracked for more than 100 km along strike, but the greatest amount of Miocene slip also coincides with parts of the footwall that were most deeply buried in the Cretaceous. These relations indicate that not only is the SKDC MMC a composite feature, but that the crustal welt created by early thickening played a fundamental role in controlling the slip distribution on subsequent extensional structures and is still evident in the high modern surface elevations of the portions of the footwall what were most deeply buried.

Carbonate sedimentology of Seribu Islands patch reef complex: a literature review

NASA Astrophysics Data System (ADS)

Utami, D. A.; Hakim, A. R.

2018-02-01

Many oil and gas reservoirs in the world are reserved in fossil carbonate sediment. Knowledge of modern carbonate sedimentology is important for a better understanding of ancient carbonate sedimentation. Equatorial coral reefs comprise almost half of the world coral reef production, and yet their dynamics, distributions, and cycles are still not well understood. Contrary to their subtropical counterpart, South East Asian carbonate system is known to be strongly influenced by the combination of oceanographic and climatic conditions. Hence carbonate sediments in the tropics have a distinct depositional system, and ought to be treated differently since common distribution models were developed from the (sub-tropical) Atlantic and Pacific regions. This paper systematically summarizes carbonate sediment studies in Seribu Islands and its dominant oceanographic configuration to provide insights and a sense of research direction in the future.

Stratigraphic and structural relationships between Meso-Cenozoic Lagonegro basin and coeval carbonate platforms in southern Apennines, Italy

NASA Astrophysics Data System (ADS)

Pescatore, Tullio; Renda, Pietro; Schiattarella, Marcello; Tramutoli, Mariano

1999-12-01

Stratigraphic studies and facies analysis integrated with a new geological and structural survey of the Meso-Cenozoic units outcropping in the Campania-Lucania Apennines, southern Italy, allowed us to restore the palaeogeographic pattern and the tectonic evolution of the chain during Oligo-Miocene times. The southern Apennines are a N150°-striking and NE-verging fold-and-thrust belt mainly derived from the deformation of the African-Apulian passive margin. Four wide belts with different features have been recognized in the chain area. From east to west the following units outcrop: (a) successions characterized by basinal to marginal facies, ranging in age from Cretaceous to Miocene, tectonically lying on Plio-Pleistocene foredeep deposits; (b) successions characterized by shallow-water, basinal and shelf-margin facies, ranging in age from middle Triassic to Miocene ('Lagonegro units'), overthrust on the previous ones; (c) Triassic to Miocene carbonate platform successions ('Apenninic platform units'), overthrust on the Lagonegro units; (d) Jurassic-Cretaceous to Miocene deep-water successions (ophiolite-bearing or 'internal' units and associated siliciclastic wedges), outcropping along the Tyrrhenian belt and the Calabria-Lucania boundary, overthrust on the Apenninic platform units. All these units tectonically lie on the buried Apulian platform which is covered, at least in the eastern sector of the chain, by Pliocene to Pleistocene foredeep deposits. Stratigraphic patterns of the Cretaceous to lower Miocene Lagonegro successions are coherent with the platform margin ones. Calcareous clastics of the Lagonegro basin are in fact supplied by an adjacent western platform, as inferred by several sedimentological evidences (slump and palaeocurrent directions and decreasing grain size towards the depocentre of the basin). Tectonic relationships among the different units of the chain — with particular emphasis on the Lagonegro and Apenninic platform units of the Lucanian segment — are shown by means of both regional and detailed geological cross-sections. The Lagonegro units constantly underlie the carbonate units originating from detachment and thrusting of the western platform and overlie the eastern (i.e. Apulian) platform. The Lagonegro units show a strong lateral variability of map-scale structures. Dome-and-basin folds are in fact largely observable in the Lucanian Apennine. Further, the belt is widely affected by Plio-Quaternary strike-slip and extensional faults. Yet, excluding the brittle deformation due to Quaternary faulting, the complexity of structural styles seems to result from the Neogene refolding of more ancient structures produced by Oligo-Miocene intraplate deformation. This hypothesis is supported by two independent lines of evidence: the first is the recognition of unconformities between the lower Miocene Numidian sandstone and the underlying Lagonegro successions, at least in the southwestern sectors; the second is that the internal (i.e. western) platform remains undeformed until the early Miocene. Both stratigraphic and structural data suggest an external position of the Meso-Cenozoic Lagonegro basin with regard to the coeval Apenninic platform.

Geologic framework of oil and gas genesis in main sedimentary basins from Romania Oprea Dicea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ionescu, N.; Morariu, C.D.

1991-03-01

Oil and gas fields located in Moldavic nappes are encompassed in Oligocene and lower Miocene formations, mostly in the marginal folds nappe, where Kliwa Sandstone sequences have high porosity, and in the Black Sea Plateau. The origin of the hydrocarbon accumulations from the Carpathian foredeep seems to be connected to the Oligocene-lower Miocene bituminous formations of the marginal folds and sub-Carpathian nappes. In the Gethic depression, the hydrocarbon accumulations originate in Oligocene and Miocene source rocks and host in structural, stratigraphical, and lithological traps. The accumulations connected with tectonic lines that outline the areal extension of the Oligocene, Miocene, andmore » Pliocene formations are in the underthrusted Moesian platform. The hydrocarbon accumulations related to the Carpathian foreland represent about 40% of all known accumulations in Romania. Most of them are located in the Moesian platform. In this unit, the oil and gas fields present a vertical distribution at different stratigraphic levels, from paleozoic to Neogene, and in all types of reservoirs, suggesting multicycles of oleogenesis, migration, accumulation, and sealing conditions. The hydrocarbon deposits known so far on the Black Sea continental plateau are confined in the Albian, Cenomanian, Turonian-Senonian, and Eocene formations. The traps are of complex type structural, lithologic, and stratigraphic. The reservoirs are sandstones, calcareous sandstones, limestones, and sands. The hydrocarbon source rocks are pelitic and siltic Oligocene formations. Other older source rocks are probably Cretaceous.« less

Early neogene history of the central American arc from Bocas del Toro, western Panama

USGS Publications Warehouse

Coates, Anthony G.; Aubry, Marie-Pierre; Berggren, William A.; Collins, Laurel S.; Kunk, Michael J.

2003-01-01

A newly discovered sequence of lower to middle Miocene rocks from the eastern Bocas del Toro archipelago, western Panama, reveals the timing and environment of the earliest stages in the rise of the Isthmus of Panama in this region. Two new formations, the Punta Alegre Formation (lower Miocene, Aquitanian to Burdigalian) and the Valiente Formation (middle Miocene, Langhian to Serravallian), are here named and formally described. The Punta Alegre Formation contains a diagnostic microfauna of benthic and planktic foraminifera and calcareous nannofossils that indicate deposition in a 2000-m-deep pre-isthmian neotropical ocean from as old as 21.5–18.3 Ma. Its lithology varies from silty mudstone to muddy foraminiferal ooze with rare thin microturbidite layers near the top. The Valiente Formation, which ranges in age from 16.4 to ca. 12.0 Ma, lies with slight angular unconformity on the Punta Alegre Formation and consists of five lithofacies: (1) columnar basalt and flow breccia, (2) pyroclastic deposits, (3) coarse-grained volcaniclastic deposits, (4) coral-reef limestone with diverse large coral colonies, and (5) marine debris-flow deposits and microturbidites. These lithofacies are interpreted to indicate that after ca. 16 Ma a volcanic arc developed in the region of Bocas del Toro and that by ca. 12 Ma an extensively emergent archipelago of volcanic islands had formed. 39Ar/40Ar dating of basalt flows associated with the fossiliferous sedimentary rocks in the upper part of the Valiente Formation strongly confirms the ages derived from planktic foraminifera and nannofossils. Paleobathymetric analysis of the two new formations in the Valiente Peninsula and Popa Island, in the Bocas del Toro archipelago, shows a general shallowing from lower- through upper-bathyal to upper-neritic and emergent laharic and fluviatile deposits from ca. 19 to 12 Ma. The overlying nonconformable Bocas del Toro Group contains a lower transgressive sequence ranging from basal nearshore sandstone to upper-bathyal mudstone (ca. 8.1–5.3 Ma) and an upper regressive sequence (5.3–3.5 Ma). A similar paleobathymetric pattern is observed from the Gatun to Chagres Formations (12–6 Ma) in the Panama Canal Basin area and in the Uscari, Rio Banana, Quebrada Chocolate, and Moin Formations (8–1.7 Ma) in the southern Limón Basin of Costa Rica.

Assessing Different Causes of Crown-of-Thorns Starfish Outbreaks and Appropriate Responses for Management on the Great Barrier Reef

PubMed Central

Babcock, Russell C.; Dambacher, Jeffrey M.; Morello, Elisabetta B.; Plagányi, Éva E.; Hayes, Keith R.; Sweatman, Hugh P. A.; Pratchett, Morgan S.

2016-01-01

The crown-of-thorns starfish Acanthaster planci (COTS) has contributed greatly to declines in coral cover on Australia’s Great Barrier Reef, and remains one of the major acute disturbances on Indo-Pacific coral reefs. Despite uncertainty about the underlying causes of outbreaks and the management responses that might address them, few studies have critically and directly compared competing hypotheses. This study uses qualitative modelling to compare hypotheses relating to outbreak initiation, explicitly considering the potential role of positive feedbacks, elevated nutrients, and removal of starfish predators by fishing. When nutrients and fishing are considered in isolation, the models indicate that a range of alternative hypotheses are capable of explaining outbreak initiation with similar levels of certainty. The models also suggest that outbreaks may be caused by multiple factors operating simultaneously, rather than by single proximal causes. As the complexity and realism of the models increased, the certainty of outcomes decreased, but key areas that require further research to improve the structure of the models were identified. Nutrient additions were likely to result in outbreaks only when COTS larvae alone benefitted from nutrients. Similarly, the effects of fishing on the decline of corals depended on the complexity of interactions among several categories of fishes. Our work suggests that management approaches which seek to be robust to model structure uncertainty should allow for multiple potential causes of outbreaks. Monitoring programs can provide tests of alternative potential causes of outbreaks if they specifically monitor all key taxa at reefs that are exposed to appropriate combinations of potential causal factors. PMID:28036360

Effects of light, food availability and temperature stress on the function of photosystem II and photosystem I of coral symbionts.

PubMed

Hoogenboom, Mia O; Campbell, Douglas A; Beraud, Eric; Dezeeuw, Katrina; Ferrier-Pagès, Christine

2012-01-01

Reef corals are heterotrophic coelenterates that achieve high productivity through their photosynthetic dinoflagellate symbionts. Excessive seawater temperature destabilises this symbiosis and causes corals to "bleach," lowering their photosynthetic capacity. Bleaching poses a serious threat to the persistence of coral reefs on a global scale. Despite expanding research on the causes of bleaching, the mechanisms remain a subject of debate. This study determined how light and food availability modulate the effects of temperature stress on photosynthesis in two reef coral species. We quantified the activities of Photosystem II, Photosystem I and whole chain electron transport under combinations of normal and stressful growth temperatures, moderate and high light levels and the presence or absence of feeding of the coral hosts. Our results show that PS1 function is comparatively robust against temperature stress in both species, whereas PS2 and whole chain electron transport are susceptible to temperature stress. In the symbiotic dinoflagellates of Stylophora pistillata the contents of chlorophyll and major photosynthetic complexes were primarily affected by food availability. In Turbinaria reniformis growth temperature was the dominant influence on the contents of the photosynthetic complexes. In both species feeding the host significantly protected photosynthetic function from high temperature stress. Our findings support the photoinhibition model of coral bleaching and demonstrate that PS1 is not a major site for thermal damage during bleaching events. Feeding mitigates bleaching in two scleractinian corals, so that reef responses to temperature stresses will likely be influenced by the coinciding availabilities of prey for the host.

Macroalgal diversity along an inshore-offshore environmental gradient in the Jakarta Bay - Thousand Islands reef complex, Indonesia

NASA Astrophysics Data System (ADS)

Draisma, Stefano G. A.; Prud'homme van Reine, Willem F.; Herandarudewi, Sekar M. C.; Hoeksema, Bert W.

2018-01-01

The Jakarta Bay - Thousand Islands reef complex extends to more than 80 km in northwest direction from the major conurbation Jakarta (Indonesia) along a pronounced inshore to offshore environmental gradient. The present study aims to determine to what extent environmental factors can explain the composition of macroalgal communities on the reefs off Jakarta. Therefore, the presence-absence of 67 macroalgal taxa was recorded for 27 sampling sites along the inshore-offshore disturbance gradient and analysed with substrate variables and water quality variables. The macroalgal richness pattern matches the pattern of other reef taxa. The 27 sites could be assigned to one of four geographical zones with 85% certainty based on their macroalgal taxon assemblages. These four zones (i.e., Jakarta Bay and, respectively, South, Central, and North Thousand Islands) had significantly different macroalgal assemblages, except for the North and South zones. Along the nearshore gradient there was a greater shift in taxon composition than within the central Thousand Islands. The patterns of ten habitat and water quality variables resembled the macroalgal diversity patterns by 56%. All ten variables together explained 69% of the variation in macroalgal composition. Shelf depth, % sand cover, gelbstoff/detrital material, chlorophyll a concentration, seawater surface temperature, and % dead coral cover were the best predictors of seaweed flora composition. Furthermore, 44 macroalgal species represented new records for the area. The present study provides important baseline data of macroalgae in the area for comparison in future biodiversity assessments in the area and elsewhere in the region.

Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands).

PubMed

Couch, Courtney S; Burns, John H R; Liu, Gang; Steward, Kanoelani; Gutlay, Tiffany Nicole; Kenyon, Jean; Eakin, C Mark; Kosaki, Randall K

2017-01-01

2014 marked the sixth and most widespread mass bleaching event reported in the Northwestern Hawaiian Islands, home to the Papahānaumokuākea Marine National Monument (PMNM), the world's second largest marine reserve. This event was associated with an unusual basin-scale warming in the North Pacific Ocean, with an unprecedented peak intensity of around 20°C-weeks of cumulative heat stress at Lisianksi Island. In situ bleaching surveys and satellite data were used to evaluate the relative importance of potential drivers of bleaching patterns in 2014, assess the subsequent morality and its effects on coral communities and 3D complexity, test for signs of regional acclimation, and investigate long-term change in heat stress in PMNM. Surveys conducted at four island/atoll (French Frigate Shoals, Lisianski Island, Pearl and Hermes Atoll, and Midway Atoll) showed that in 2014, percent bleaching varied considerably between islands/atolls and habitats (back reef/fore reef and depth), and was up to 91% in shallow habitats at Lisianski. The percent bleaching during the 2014 event was best explained by a combination of duration of heat stress measured by Coral Reef Watch's satellite Degree Heating Week, relative community susceptibility (bleaching susceptibility score of each taxon * the taxon's abundance relative to the total number of colonies), depth and region. Mean coral cover at permanent Lisianski monitoring sites decreased by 68% due to severe losses of Montipora dilatata complex, resulting in rapid reductions in habitat complexity. Spatial distribution of the 2014 bleaching was significantly different from the 2002 and 2004 bleaching events likely due to a combination of differences in heat stress and local acclimatization. Historical satellite data demonstrated heat stress in 2014 was unlike any previous event and that the exposure of corals to the bleaching-level heat stress has increased significantly in the northern PMNM since 1982, highlighting the increasing threat of climate change to reefs.

Ten years of change to coral communities off Mona and Desecheo Islands, Puerto Rico, from disease and bleaching.

PubMed

Bruckner, Andrew W; Hill, Ronald L

2009-11-16

Remote reefs off southwest Puerto Rico have experienced recent losses in live coral cover of 30 to 80%, primarily due to the decline of Montastraea annularis and M. faveolata from disease and bleaching. These species were formerly the largest, oldest, and most abundant corals on these reefs, constituting over 65% of the living coral cover and 40 to 80% of the total number of colonies. From 1998 to 2001, outbreaks of yellow band disease (YBD) and white plague (WP) affected 30 to 60% of the M. annularis (complex) colonies. Disease prevalence declined beginning in 2002, and then increased immediately following the 2005 mass bleaching event. Colonies of M. annularis (complex) have been reduced in abundance by 24 to 32%, and remaining colonies are missing more than half their tissue. Both M. annularis and M. faveolata have failed to recruit, resheeting has been minimal, and exposed skeletal surfaces are being colonized by macroalgae, bioeroding sponges, and hydrozoans. Other scleractinian corals were smaller in size (mean = 28 cm diameter) and exhibited lower levels of partial mortality; these taxa were affected to a lesser extent by coral diseases and bleaching-associated tissue loss over the last decade. The numbers of small colonies (1 to 9 cm) of these species identified since 2005 also exceeded numbers of larger colonies that died. These reefs appear to be exhibiting shifts in species assemblages, with replacement of M. annularis (complex) by shorter-lived brooding species and other massive and plating corals (Agaricia, Porites, Meandrina, Eusmilia, Diploria, and Siderastrea spp.). To avoid a catastrophic and permanent loss of the dominant, slow-growing reef-building corals, the causes and effects of diseases need to be better understood, and possible control mechanisms must be developed. In particular, steps must be taken to mitigate environmental and anthropogenic stressors that increase the spread and severity of disease.

Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands)

PubMed Central

Couch, Courtney S.; Burns, John H. R.; Liu, Gang; Steward, Kanoelani; Gutlay, Tiffany Nicole; Kenyon, Jean; Eakin, C. Mark; Kosaki, Randall K.

2017-01-01

2014 marked the sixth and most widespread mass bleaching event reported in the Northwestern Hawaiian Islands, home to the Papahānaumokuākea Marine National Monument (PMNM), the world’s second largest marine reserve. This event was associated with an unusual basin-scale warming in the North Pacific Ocean, with an unprecedented peak intensity of around 20°C-weeks of cumulative heat stress at Lisianksi Island. In situ bleaching surveys and satellite data were used to evaluate the relative importance of potential drivers of bleaching patterns in 2014, assess the subsequent morality and its effects on coral communities and 3D complexity, test for signs of regional acclimation, and investigate long-term change in heat stress in PMNM. Surveys conducted at four island/atoll (French Frigate Shoals, Lisianski Island, Pearl and Hermes Atoll, and Midway Atoll) showed that in 2014, percent bleaching varied considerably between islands/atolls and habitats (back reef/fore reef and depth), and was up to 91% in shallow habitats at Lisianski. The percent bleaching during the 2014 event was best explained by a combination of duration of heat stress measured by Coral Reef Watch’s satellite Degree Heating Week, relative community susceptibility (bleaching susceptibility score of each taxon * the taxon’s abundance relative to the total number of colonies), depth and region. Mean coral cover at permanent Lisianski monitoring sites decreased by 68% due to severe losses of Montipora dilatata complex, resulting in rapid reductions in habitat complexity. Spatial distribution of the 2014 bleaching was significantly different from the 2002 and 2004 bleaching events likely due to a combination of differences in heat stress and local acclimatization. Historical satellite data demonstrated heat stress in 2014 was unlike any previous event and that the exposure of corals to the bleaching-level heat stress has increased significantly in the northern PMNM since 1982, highlighting the increasing threat of climate change to reefs. PMID:28953909

Ocean acidification can mediate biodiversity shifts by changing biogenic habitat

NASA Astrophysics Data System (ADS)

Sunday, Jennifer M.; Fabricius, Katharina E.; Kroeker, Kristy J.; Anderson, Kathryn M.; Brown, Norah E.; Barry, James P.; Connell, Sean D.; Dupont, Sam; Gaylord, Brian; Hall-Spencer, Jason M.; Klinger, Terrie; Milazzo, Marco; Munday, Philip L.; Russell, Bayden D.; Sanford, Eric; Thiyagarajan, Vengatesen; Vaughan, Megan L. H.; Widdicombe, Stephen; Harley, Christopher D. G.

2017-01-01

The effects of ocean acidification (OA) on the structure and complexity of coastal marine biogenic habitat have been broadly overlooked. Here we explore how declining pH and carbonate saturation may affect the structural complexity of four major biogenic habitats. Our analyses predict that indirect effects driven by OA on habitat-forming organisms could lead to lower species diversity in coral reefs, mussel beds and some macroalgal habitats, but increases in seagrass and other macroalgal habitats. Available in situ data support the prediction of decreased biodiversity in coral reefs, but not the prediction of seagrass bed gains. Thus, OA-driven habitat loss may exacerbate the direct negative effects of OA on coastal biodiversity; however, we lack evidence of the predicted biodiversity increase in systems where habitat-forming species could benefit from acidification. Overall, a combination of direct effects and community-mediated indirect effects will drive changes in the extent and structural complexity of biogenic habitat, which will have important ecosystem effects.

Interaction between Coastal and Oceanic Ecosystems of the Western and Central Pacific Ocean through Predator-Prey Relationship Studies

PubMed Central

Allain, Valerie; Fernandez, Emilie; Hoyle, Simon D.; Caillot, Sylvain; Jurado-Molina, Jesus; Andréfouët, Serge; Nicol, Simon J.

2012-01-01

The Western and Central Pacific Ocean sustains the highest tuna production in the world. This province is also characterized by many islands and a complex bathymetry that induces specific current circulation patterns with the potential to create a high degree of interaction between coastal and oceanic ecosystems. Based on a large dataset of oceanic predator stomach contents, our study used generalized linear models to explore the coastal-oceanic system interaction by analyzing predator-prey relationship. We show that reef organisms are a frequent prey of oceanic predators. Predator species such as albacore (Thunnus alalunga) and yellowfin tuna (Thunnus albacares) frequently consume reef prey with higher probability of consumption closer to land and in the western part of the Pacific Ocean. For surface-caught-predators consuming reef prey, this prey type represents about one third of the diet of predators smaller than 50 cm. The proportion decreases with increasing fish size. For predators caught at depth and consuming reef prey, the proportion varies with predator species but generally represents less than 10%. The annual consumption of reef prey by the yellowfin tuna population was estimated at 0.8±0.40CV million tonnes or 2.17×1012±0.40CV individuals. This represents 6.1%±0.17CV in weight of their diet. Our analyses identify some of the patterns of coastal-oceanic ecosystem interactions at a large scale and provides an estimate of annual consumption of reef prey by oceanic predators. PMID:22615796

Habitat characteristics affecting fish assemblages on a Hawaiian coral reef

USGS Publications Warehouse

Friedlander, A.M.; Parrish, J.D.

1998-01-01

Habitat characteristics of a reef were examined as potential influences on fish assemblage structure, using underwater visual census to estimate numbers and biomass of all fishes visible on 42 benthic transects and making quantitative measurements of 13 variables of the corresponding physical habitat and sessile biota. Fish assemblages in the diverse set of benthic habitats were grouped by detrended correspondence analysis, and associated with six major habitat types. Statistical differences were shown between a number of these habitat types for various ensemble variables of the fish assemblages. Overall, both for complete assemblages and for component major trophic and mobility guilds, these variables tended to have higher values where reef substratum was more structurally or topographically complex, and closer to reef edges. When study sites were separately divided into five depth strata, the deeper strata tended to have statistically higher values of ensemble variables for the fish assemblages. Patterns with depth varied among the various trophic and mobility guilds. Multiple linear regression models indicated that for the complete assemblages and for most trophic and mobility guilds, a large part of the variability for most ensemble variables was explained by measures of holes in the substratum, with important contributions from measured substratum rugosity and depth. A strong linear relationship found by regression of mean fish length on mean volume of holes in the reef surface emphasized the importance of shelter for fish assemblages. Results of this study may have practical applications in designing reserve areas as well as theoretical value in helping to explain the organization of reef fish assemblages.

The Microbial Signature Provides Insight into the Mechanistic Basis of Coral Success across Reef Habitats

PubMed Central

Leggat, William; Bongaerts, Pim

2016-01-01

ABSTRACT For ecosystems vulnerable to environmental change, understanding the spatiotemporal stability of functionally crucial symbioses is fundamental to determining the mechanisms by which these ecosystems may persist. The coral Pachyseris speciosa is a successful environmental generalist that succeeds in diverse reef habitats. The generalist nature of this coral suggests it may have the capacity to form functionally significant microbial partnerships to facilitate access to a range of nutritional sources within different habitats. Here, we propose that coral is a metaorganism hosting three functionally distinct microbial interactions: a ubiquitous core microbiome of very few symbiotic host-selected bacteria, a microbiome of spatially and/or regionally explicit core microbes filling functional niches (<100 phylotypes), and a highly variable bacterial community that is responsive to biotic and abiotic processes across spatial and temporal scales (>100,000 phylotypes). We find that this coral hosts upwards of 170,000 distinct phylotypes and provide evidence for the persistence of a select group of bacteria in corals across environmental habitats of the Great Barrier Reef and Coral Sea. We further show that a higher number of bacteria are consistently associated with corals on mesophotic reefs than on shallow reefs. An increase in microbial diversity with depth suggests reliance by this coral on bacteria for nutrient acquisition on reefs exposed to nutrient upwelling. Understanding the complex microbial communities of host organisms across broad biotic and abiotic environments as functionally distinct microbiomes can provide insight into those interactions that are ubiquitous niche symbioses and those that provide competitive advantage within the hosts’ environment. PMID:27460792

Climate-Smart Design for Ecosystem Management: A Test Application for Coral Reefs.

PubMed

West, Jordan M; Courtney, Catherine A; Hamilton, Anna T; Parker, Britt A; Julius, Susan H; Hoffman, Jennie; Koltes, Karen H; MacGowan, Petra

2017-01-01

The interactive and cumulative impacts of climate change on natural resources such as coral reefs present numerous challenges for conservation planning and management. Climate change adaptation is complex due to climate-stressor interactions across multiple spatial and temporal scales. This leaves decision makers worldwide faced with local, regional, and global-scale threats to ecosystem processes and services, occurring over time frames that require both near-term and long-term planning. Thus there is a need for structured approaches to adaptation planning that integrate existing methods for vulnerability assessment with design and evaluation of effective adaptation responses. The Corals and Climate Adaptation Planning project of the U.S. Coral Reef Task Force seeks to develop guidance for improving coral reef management through tailored application of a climate-smart approach. This approach is based on principles from a recently-published guide which provides a framework for adopting forward-looking goals, based on assessing vulnerabilities to climate change and applying a structured process to design effective adaptation strategies. Work presented in this paper includes: (1) examination of the climate-smart management cycle as it relates to coral reefs; (2) a compilation of adaptation strategies for coral reefs drawn from a comprehensive review of the literature; (3) in-depth demonstration of climate-smart design for place-based crafting of robust adaptation actions; and (4) feedback from stakeholders on the perceived usefulness of the approach. We conclude with a discussion of lessons-learned on integrating climate-smart design into real-world management planning processes and a call from stakeholders for an "adaptation design tool" that is now under development.

Effects of predation on diel activity and habitat use of the coral-reef shrimp Cinetorhynchus hendersoni (Rhynchocinetidae)

NASA Astrophysics Data System (ADS)

Ory, Nicolas C.; Dudgeon, David; Duprey, Nicolas; Thiel, Martin

2014-09-01

Nonlethal effects of predators on prey behaviour are still poorly understood, although they may have cascading effects through food webs. Underwater observations and experiments were conducted on a shallow fringing coral reef in Malaysia to examine whether predation risks affect diel activity, habitat use, and survival of the rhynchocinetid shrimp Cinetorhynchus hendersoni. The study site was within a protected area where predatory fish were abundant. Visual surveys and tethering experiments were conducted in April-May 2010 to compare the abundance of shrimps and predatory fishes and the relative predation intensity on shrimps during day and night. Shrimps were not seen during the day but came out of refuges at night, when the risk of being eaten was reduced. Shrimp preferences for substrata of different complexities and types were examined at night when they could be seen on the reef; complex substrata were preferred, while simple substrata were avoided. Shrimps were abundant on high-complexity columnar-foliate Porites rus, but tended to make little use of branching Acropora spp. Subsequent tethering experiments, conducted during daytime in June 2013, compared the relative mortality of shrimps on simple (sand-rubble, massive Porites spp.) and complex ( P. rus, branching Acropora spp.) substrata under different predation risk scenarios (i.e., different tether lengths and exposure durations). The mortality of shrimps with short tethers (high risk) was high on all substrata while, under low and intermediate predation risks (long tethers), shrimp mortality was reduced on complex corals relative to that on sand-rubble or massive Porites spp. Overall, mortality was lowest on P. rus. Our study indicates that predation risks constrain shrimp activity and habitat choice, forcing them to hide deep inside complex substrata during the day. Such behavioural responses to predation risks and their consequences for the trophic role of invertebrate mesoconsumers warrant further investigation, especially in areas where predatory fishes have been overexploited.

A mineralogical perspective on the recovery of platinum group elements from Merensky Reef and UG2 at the Two Rivers mine on the Eastern limb of the Bushveld Complex in South Africa

NASA Astrophysics Data System (ADS)

Rose, Derek H.; Viljoen, K. S.; Mulaba-Bafubiandi, Antoine

2018-06-01

Published studies dealing with the process mineralogy of Pt mines on the Bushveld Complex is generally limited to the Western Bushveld. The recognition by mine management that another resource, in addition to the Upper Group 2 (UG2) reef currently being mined at the Two Rivers platinum mine (TRP), is urgently required in order to extend the life of mine, presented an opportunity to conduct such a study on the Eastern Limb of the Bushveld Complex. A process mineralogical investigation was undertaken on ore from the Merensky Reef (MR) and the UG2 at TRP. This was conducted on a suite of geological samples (channel samples) collected from the underground workings, as well as metallurgical samples obtained from the rougher circuits at the concentrator plant during the processing of MR and UG2 ore. The geological and metallurgical samples were analysed for bulk composition and quantitative mineralogy, while the geological samples were also subjected to laboratory-scale milling and flotation tests. This study shows that, although mineralogically distinct, the MR and UG2 behave similarly in terms of metallurgical performance. This holds promise for the proposed blending of MR and UG2 ores at TRP. An evaluation of the bulk rock (ore) Pt/Pd ratio as a possible indicator of the level of hydrothermal alteration of the ore, demonstrates that this may be of use in predicting recovery plant performance.

Recruitment, mortality, and resilience potential of scleractinian corals at Eilat, Red Sea

NASA Astrophysics Data System (ADS)

Shlesinger, Tom; Loya, Yossi

2016-12-01

Events of mass coral bleaching and mortality have increased in recent decades worldwide, making coral recruitment more important than ever in sustaining coral-reef ecosystems and ensuring their resilience. During the last four decades, the coral reefs of Eilat have undergone severe deterioration due to both anthropogenic and natural causes. Recruitment failure has been frequently suggested as one of the main mechanisms underlying this deterioration. Here we assess the demographic replenishment and resilience potential of the local reefs, i.e., the potential for new sexually derived corals to recruit and exceed the community's mortality rate. We present a detailed analysis of coral community demography, obtained by means of high-resolution photographic monitoring of permanently marked plots. Coral spats as small as 1 mm were documented and the detailed dynamics of coral recruitment and mortality were recorded, in addition to other common ecological measurements. The cumulative quantity of recruited individuals was twofold to fivefold higher than total mortality. The most significant predictor variable for coral recruitment among all ecological parameters measured was the available substrate for settlement, and the survival of recruited corals was correlated with reef structural complexity. Two consecutive annual reproductive seasons (June-September of each year) with high recruitment rates were monitored. Combined with the high survival of recruits and the increase in coral live cover and abundance, the findings from this study indicate an encouraging potential for recovery of these reefs.

Changes in Caribbean coral disease prevalence after the 2005 bleaching event.

PubMed

Cróquer, Aldo; Weil, Ernesto

2009-11-16

Bleaching events and disease epizootics have increased during the past decades, suggesting a positive link between these 2 causes in producing coral mortality. However, studies to test this hypothesis, integrating a broad range of hierarchical spatial scales from habitats to distant localities, have not been conducted in the Caribbean. In this study, we examined links between bleaching intensity and disease prevalence collected from 6 countries, 2 reef sites for each country, and 3 habitats within each reef site (N = 6 x 2 x 3 = 36 site-habitat combinations) during the peak of bleaching in 2005 and a year after, in 2006. Patterns of disease prevalence and bleaching were significantly correlated (Rho = 0.58, p = 0.04). Higher variability in disease prevalence after bleaching occurred among habitats at each particular reef site, with a significant increase in prevalence recorded in 4 of the 10 site-habitats where bleaching was intense and a non-significant increase in disease prevalence in 18 out of the 26 site-habitats where bleaching was low to moderate. A significant linear correlation was found (r = 0.89, p = 0.008) between bleaching and the prevalence of 2 virulent diseases (yellow band disease and white plague) affecting the Montastraea species complex. Results of this study suggest that if bleaching events become more intense and frequent, disease-related mortality of Caribbean coral reef builders could increase, with uncertain effects on coral reef resilience.

Enhanced macroboring and depressed calcification drive net dissolution at high-CO2 coral reefs.

PubMed

Enochs, Ian C; Manzello, Derek P; Kolodziej, Graham; Noonan, Sam H C; Valentino, Lauren; Fabricius, Katharina E

2016-11-16

Ocean acidification (OA) impacts the physiology of diverse marine taxa; among them corals that create complex reef framework structures. Biological processes operating on coral reef frameworks remain largely unknown from naturally high-carbon-dioxide (CO 2 ) ecosystems. For the first time, we independently quantified the response of multiple functional groups instrumental in the construction and erosion of these frameworks (accretion, macroboring, microboring, and grazing) along natural OA gradients. We deployed blocks of dead coral skeleton for roughly 2 years at two reefs in Papua New Guinea, each experiencing volcanically enriched CO 2 , and employed high-resolution micro-computed tomography (micro-CT) to create three-dimensional models of changing skeletal structure. OA conditions were correlated with decreased calcification and increased macroboring, primarily by annelids, representing a group of bioeroders not previously known to respond to OA. Incubation of these blocks, using the alkalinity anomaly methodology, revealed a switch from net calcification to net dissolution at a pH of roughly 7.8, within Intergovernmental Panel on Climate Change's (IPCC) predictions for global ocean waters by the end of the century. Together these data represent the first comprehensive experimental study of bioerosion and calcification from a naturally high-CO 2 reef ecosystem, where the processes of accelerated erosion and depressed calcification have combined to alter the permanence of this essential framework habitat. © 2016 The Authors.

Enhanced macroboring and depressed calcification drive net dissolution at high-CO2 coral reefs

PubMed Central

Manzello, Derek P.; Kolodziej, Graham; Noonan, Sam H. C.; Valentino, Lauren; Fabricius, Katharina E.

2016-01-01

Ocean acidification (OA) impacts the physiology of diverse marine taxa; among them corals that create complex reef framework structures. Biological processes operating on coral reef frameworks remain largely unknown from naturally high-carbon-dioxide (CO2) ecosystems. For the first time, we independently quantified the response of multiple functional groups instrumental in the construction and erosion of these frameworks (accretion, macroboring, microboring, and grazing) along natural OA gradients. We deployed blocks of dead coral skeleton for roughly 2 years at two reefs in Papua New Guinea, each experiencing volcanically enriched CO2, and employed high-resolution micro-computed tomography (micro-CT) to create three-dimensional models of changing skeletal structure. OA conditions were correlated with decreased calcification and increased macroboring, primarily by annelids, representing a group of bioeroders not previously known to respond to OA. Incubation of these blocks, using the alkalinity anomaly methodology, revealed a switch from net calcification to net dissolution at a pH of roughly 7.8, within Intergovernmental Panel on Climate Change's (IPCC) predictions for global ocean waters by the end of the century. Together these data represent the first comprehensive experimental study of bioerosion and calcification from a naturally high-CO2 reef ecosystem, where the processes of accelerated erosion and depressed calcification have combined to alter the permanence of this essential framework habitat. PMID:27852802

Middle and upper Miocene natural gas sands in onshore and offshore Alabama

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mink, R.M.; Mancini, E.A.; Bearden, B.L.

1988-09-01

Thirty Miocene natural gas fields have been established in onshore and offshore Alabama since the discovery of Miocene gas in this area in 1979. These fields have produced over 16 bcf of natural gas from the middle Miocene Amos sand (24 fields) and upper Miocene Luce (3 fields), Escambia (1 field), and Meyer (3 fields) sands. Production from the Amos transgressive sands represents over 92% of the cumulative shallow Miocene natural gas produced in onshore and offshore Alabama. In addition, over 127 bcf of natural gas has been produced from upper Miocene sands in the Chandeleur area. The productive Miocenemore » section in onshore and coastal Alabama is interpreted to present transgressive marine shelf and regressive shoreface sands. The middle Miocene Amos sand bars are the most productive reservoirs of natural gas in onshore and coastal Alabama, principally due to the porous and permeable nature of these transgressive sands and their stratigraphic relationship to the underlying basinal clays in this area. In offshore Alabama the upper Miocene sands become thicker and are generally more porous and permeable than their onshore equivalents. Because of their deeper burial depth in offshore Alabama, these upper Miocene sands are associated with marine clays that are thermally more mature. The combination of reservoir grade lithologies associated with moderately mature petroleum source rocks enhances the natural gas potential of the upper Miocene sands in offshore Alabama.« less

The Eocene-Miocene tectonic evolution of the Rif chain (Morocco): new data from the Jebha area

NASA Astrophysics Data System (ADS)

D'Assisi Tramparulo, Francesco; Ciarcia, Sabatino; El Ouaragli, Bilal; Vitale, Stefano; Najib Zaghloul, Mohamed

2016-04-01

Keywords: structural analysis, tectonics, shear bands, Miocene, Jebha Fault The Jebha area, located in the Central Rif, is a key sector to understand the orogenic evolution of the Rif chain. Here, the left lateral Jebha-Chrafate transfer fault, allowed, in the Miocene time, the westward migration of the internal thrust front. The structural analysis of the area revealed a complex tectonic history. The Eocene orogenic pulse produced the tectonic stacking of the Ghomaride thrust sheets. During the late Aquitanian and Langhian, under a dominant ENE-WSW shortening, imbrication of several Internal Dorsale Calcaire slices occurred. The following orogenic stage, characterized by a main SE tectonic transport, allowed the External Dorsale Calcaire to overthrust the Maghrebian Flysch Basin Units by means of a dominant thin-skinned tectonics. Synchronously with the buttressing following the collision of the allochthonous wedge against the External Rif domain, an out-of-sequence thrusting stage involved the Ghomaride and Dorsale Calcaire Units and a general back-thrusting deformed the entire tectonic pile. A renewal of the NE-SW shortening produced strike-slip faults and SW-verging folds and finally a radial extension affected the whole chain.

Diversity dynamics of Miocene mammals in relation to the history of tectonism and climate

PubMed Central

Finarelli, John A.; Badgley, Catherine

2010-01-01

Continental biodiversity gradients result not only from ecological processes, but also from evolutionary and geohistorical processes involving biotic turnover in landscape and climatic history over millions of years. Here, we investigate the evolutionary and historical contributions to the gradient of increasing species richness with topographic complexity. We analysed a dataset of 418 fossil rodent species from western North America spanning 25 to 5 Ma. We compared diversification histories between tectonically active (Intermontane West) and quiescent (Great Plains) regions. Although diversification histories differed between the two regions, species richness, origination rate and extinction rate per million years were not systematically different over the 20 Myr interval. In the tectonically active region, the greatest increase in originations coincided with a Middle Miocene episode of intensified tectonic activity and global warming. During subsequent global cooling, species richness declined in the montane region and increased on the Great Plains. These results suggest that interactions between tectonic activity and climate change stimulate diversification in mammals. The elevational diversity gradient characteristic of modern mammalian faunas was not a persistent feature over geologic time. Rather, the Miocene rodent record suggests that the elevational diversity gradient is a transient feature arising during particular episodes of Earth's history. PMID:20427339

Insights into the historical construction of species-rich Mesoamerican seasonally dry tropical forests: the diversification of Bursera (Burseraceae, Sapindales).

PubMed

De-Nova, J Arturo; Medina, Rosalinda; Montero, Juan Carlos; Weeks, Andrea; Rosell, Julieta A; Olson, Mark E; Eguiarte, Luis E; Magallón, Susana

2012-01-01

• Mesoamerican arid biomes epitomize neotropical rich and complex biodiversity. To document some of the macroevolutionary processes underlying the vast species richness of Mesoamerican seasonally dry tropical forests (SDTFs), and to evaluate specific predictions about the age, geographical structure and niche conservatism of SDTF-centered woody plant lineages, the diversification of Bursera is reconstructed. • Using a nearly complete Bursera species-level phylogeny from nuclear and plastid genomic markers, we estimate divergence times, test for phylogenetic and temporal diversification heterogeneity, test for geographical structure, and reconstruct habitat shifts. • Bursera became differentiated in the earliest Eocene, but diversified during independent early Miocene consecutive radiations that took place in SDTFs. The late Miocene average age of Bursera species, the presence of phylogenetic geographical structure, and its strong conservatism to SDTFs conform to expectations derived from South American SDTF-centered lineages. • The diversification of Bursera suggests that Mesoamerican SDTF richness derives from high speciation from the Miocene onwards uncoupled from habitat shifts, during a period of enhanced aridity resulting mainly from global cooling and regional rain shadows. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

The complete mitochondrial genome of the cryptic "lineage B" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) in Indo-West Pacific.

PubMed

Shen, Kang-Ning; Yen, Ta-Chi; Chen, Ching-Hung; Ye, Jeng-Jia; Hsiao, Chung-Der

2016-05-01

In this study, the complete mitogenome sequence of the cryptic "lineage B" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) has been sequenced by next-generation sequencing method. The assembled mitogenome consisting of 16,694 bp, includes 13 protein coding genes, 25 transfer RNAs, 2 ribosomal RNAs genes. The overall base composition of "lineage B" S. lessoniana is 36.7% for A, 18.9 % for C, 34.5 % for T and 9.8 % for G and show 90% identities to "lineage C" S. lessoniana. It is also exhibits high T + A content (71.2%), two non-coding regions with TA tandem repeats. The complete mitogenome of the cryptic "lineage B" S. lessoniana provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for big-fin reef squid species complex.

The complete mitochondrial genome of the cryptic "lineage A" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) in Indo-West Pacific.

PubMed

Hsiao, Chung-Der; Shen, Kang-Ning; Ching, Tzu-Yun; Wang, Ya-Hsien; Ye, Jeng-Jia; Tsai, Shiou-Yi; Wu, Shan-Chun; Chen, Ching-Hung; Wang, Chia-Hui

2016-07-01

In this study, the complete mitogenome sequence of the cryptic "lineage A" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consists of 16,605 bp, which includes 13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs genes. The overall base composition of "lineage A" S. lessoniana is 37.5% for A, 17.4% for C, 9.1% for G, and 35.9% for T and shows 87% identities to "lineage C" S. lessoniana. It is also noticed by its high T + A content (73.4%), two non-coding regions with TA tandem repeats. The complete mitogenome of the cryptic "lineage A" S. lessoniana provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for big-fin reef squid species complex.

Evolution of complex symbiotic relationships in a morphologically derived family of lichen-forming fungi.

PubMed

Divakar, Pradeep K; Crespo, Ana; Wedin, Mats; Leavitt, Steven D; Hawksworth, David L; Myllys, Leena; McCune, Bruce; Randlane, Tiina; Bjerke, Jarle W; Ohmura, Yoshihito; Schmitt, Imke; Boluda, Carlos G; Alors, David; Roca-Valiente, Beatriz; Del-Prado, Ruth; Ruibal, Constantino; Buaruang, Kawinnat; Núñez-Zapata, Jano; Amo de Paz, Guillermo; Rico, Víctor J; Molina, M Carmen; Elix, John A; Esslinger, Theodore L; Tronstad, Inger Kristin K; Lindgren, Hanna; Ertz, Damien; Gueidan, Cécile; Saag, Lauri; Mark, Kristiina; Singh, Garima; Dal Grande, Francesco; Parnmen, Sittiporn; Beck, Andreas; Benatti, Michel Navarro; Blanchon, Dan; Candan, Mehmet; Clerc, Philippe; Goward, Trevor; Grube, Martin; Hodkinson, Brendan P; Hur, Jae-Seoun; Kantvilas, Gintaras; Kirika, Paul M; Lendemer, James; Mattsson, Jan-Eric; Messuti, María Inés; Miadlikowska, Jolanta; Nelsen, Matthew; Ohlson, Jan I; Pérez-Ortega, Sergio; Saag, Andres; Sipman, Harrie J M; Sohrabi, Mohammad; Thell, Arne; Thor, Göran; Truong, Camille; Yahr, Rebecca; Upreti, Dalip K; Cubas, Paloma; Lumbsch, H Thorsten

2015-12-01

We studied the evolutionary history of the Parmeliaceae (Lecanoromycetes, Ascomycota), one of the largest families of lichen-forming fungi with complex and variable morphologies, also including several lichenicolous fungi. We assembled a six-locus data set including nuclear, mitochondrial and low-copy protein-coding genes from 293 operational taxonomic units (OTUs). The lichenicolous lifestyle originated independently three times in lichenized ancestors within Parmeliaceae, and a new generic name is introduced for one of these fungi. In all cases, the independent origins occurred c. 24 million yr ago. Further, we show that the Paleocene, Eocene and Oligocene were key periods when diversification of major lineages within Parmeliaceae occurred, with subsequent radiations occurring primarily during the Oligocene and Miocene. Our phylogenetic hypothesis supports the independent origin of lichenicolous fungi associated with climatic shifts at the Oligocene-Miocene boundary. Moreover, diversification bursts at different times may be crucial factors driving the diversification of Parmeliaceae. Additionally, our study provides novel insight into evolutionary relationships in this large and diverse family of lichen-forming ascomycetes. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Two-stage Uplift of Granite-Gneiss-Migmatite Complex (GGMC) of Çataldaǧ Core Complex (Western Anatolia, Turkey): the role of detachment faults on uplift processes

NASA Astrophysics Data System (ADS)

Kamaci, Omer; Altunkaynak, Safak

2016-04-01

The most recently identified core complex of western Anatolia (Turkey), the Çataldaǧ Core Complex (ÇCC) consists of a granite-gneiss-migmatite complex (GGMC) representing deep crustal rocks of NW Turkey and a shallow level granodioritic body (ÇG: Çataldaǧ granodiorite). The GGMC is Latest Eocene-Early Oligocene and ÇG is Early Miocene in age, and both were exhumed in the footwall of the Çataldaǧ Detachment Fault Zone (ÇDFZ) in the Early Miocene. On the basis of correlation of age data and the closure temperatures of zircon, monazite, muscovite, biotite and K-feldspar, the T-time history of GGMC reveals that GGMC has experienced at least two stages of cooling and uplift, from 33.8 to 30.1 Ma and 21.3 to 20.7 Ma. In stage I, from 33.8 to 30.1 Ma, the cooling rate of GGMC was relatively slow (35°C/my) however cooling rate increase dramatically to ≥500°C/my in stage II between 21.3 and 20.7 Ma. T-time history also indicate that GGMC was elevated to the final location in at least 8-13 My according to the monazite and zircon and mica ages obtained from the same rock. Rapid slab rollback at the Hellenic trench at ca. 23 Ma may have increased extension rates leading to the development of detachment faults (i.e. ÇDFZ), core complexes and associated syn-extensional granitoids in Western Anatolia and the Aegean extensional province.

Preliminary Paleomagnetically Determined Vertical-Axis Rotations and their Relationship to Extensional Events of the Southern Walker Lane

NASA Astrophysics Data System (ADS)

Johnson, S.; Geissman, J. W.; Katopody, D. T.; Kerstetter, S. R.; Oldow, J. S.

2016-12-01

The northern part of the southern Walker Lane experienced three extensional events from the late Oligocene to the Holocene: 1) late Oligocene to early Miocene WNW and ENE trending half-grabens, 2) Late Miocene to early Pliocene high-magnitude extension on a low-angle normal fault, and 3) contemporary transtensional deformation that initiated at 4 Ma. Each of the extensional events controlled deposition of synextensional strata. What is less understood is the timing and magnitude of vertical axis rotation and its relationship to each of the three extensional events. As part of a recent and ongoing multidisciplinary study to better understand the complex nature and history of these extensional events we present preliminary paleomagnetic data from 55 sites in Miocene extrusive igneous rocks which record that clockwise vertical-axis rotation played a significant role in accommodating displacement in these systems. Recently refined stratigraphic, geochronologic, and structural controls have allowed the detailed paleomagnetic sampling required for this study. We seek to provide better constraints on timing, areal extent, and distribution of vertical axis rotation to answer how vertical axis rotation interacted with these extensional events. Consistent with past studies, we have recognized 20-30 degrees of clockwise vertical-axis rotation distributed heterogeneously throughout the study area. However, clockwise vertical-axis rotations are no longer occurring in this region as evidenced by modern geodetic velocity fields. The accommodation of displacement by vertical axis rotations in this region likely ceased by early Pliocene to late Miocene when the structural step-over migrated to the northwest to its present day manifestation in the Mina Deflection. Anisotropy of magnetic susceptibility (AMS), used as a proxy for flow direction in igneous extrusive rocks, provides evidence that at least one late Oligocene-early Miocene half-grabens acted as near-source depositional centers concurrent with extension.

St. Croix, U.S. Virgin Islands, Caribbean Sea

NASA Image and Video Library

1993-01-19

STS054-74-049 (13-19 Jan. 1993) --- St. Croix is the largest, and most industrial of the U.S. Virgin Islands. This photograph captures St. Croix's features in great detail. The large industrial complex in the middle of the southern shore is the world's largest petroleum refinery. The main city, Christiansted, can be seen across the island on the north shore. The reefs around the eastern end of St. Croix are preserved as a submarine national park -- Buck Island Reef National Park -- around the small island off the north shore of the eastern end of St. Croix.

Oolite facies as a transitional unit in deepening-upward carbonate sequences in Atoll, Seamount, and Guyot settings in Pacific basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlanger, S.O.

Prior to 1968, ooids had not been described from shallow-water carbonate complexes deposited in atoll, seamount, or guyot settings in the Pacific basin. This apparent lack of an oolite facies in the Pacific was puzzling, considering the abundance of ooids in modern Bahamian settings and in the Phanerozoic record in general. Since 1968, Deep Sea Drilling Project operations, marine seismic stratigraphic studies, dredging on drowned atolls, and field studies of an emergent atoll have revealed the presence of a Cretaceous oolite limestone atop Ita Maitai Guyot, Paleocene ooids on Koko Seamount, late Paleocene to middle Eocene ooids on Ojin Seamount,more » Eocene ooids on Harrie Guyot, and Holocene oolite limestone on Malden Island. At Ita Maitai Guyot the oolite limestone overlies normal lagoon sediments and is overlain by deep-water pelagic carbonate. At Malden Island, which is an emergent atoll, 3550-year-old oolite limestone overlies a 125,000-year-old reef complex. At Harrie Guyot and at Koko and Ojin Seamounts, ooids are associated with drowned atoll reef and lagoon complexes. The paleolatitude of deposition of the oolite facies lay between 5/sup 0/S and 18/sup 0/N. In these settings the formation of the oolite facies was apparently related to a rapid rise in sea level that caused flooding of an antecedent reef complex which failed to keep up with the rise in sea level. In Pacific basin environments the oolite facies is a minor and temporally ephemeral one which accounts for its scarcity in the stratigraphic record from this region.« less

Miocene vegetation shift and climate change: Evidence from the Siwalik of Nepal

NASA Astrophysics Data System (ADS)

Srivastava, Gaurav; Paudayal, Khum N.; Utescher, Torsten; Mehrotra, R. C.

2018-02-01

We reconstruct climate and vegetation applying the Coexistence Approach (CA) methodology on two palaeofloras recovered from the Lower (middle Miocene; 13-11 Ma) and Middle Siwalik (late Miocene; 9.5-6.8 Ma) sediments of Surai Khola section, Nepal. The reconstructed mean annual temperature (MAT) and cold month mean temperature (CMT) show an increasing trend, while warm month mean temperature (WMT) remains nearly the same during the period. The reconstructed precipitation data indicates that the summer monsoon precipitation was nearly the same during the middle and late Miocene, while the winter season precipitation significantly decreased in the late Miocene. The overall precipitation infers increased rainfall seasonality during the late Miocene. The vegetation during the middle Miocene was dominated by wet evergreen taxa, whereas deciduous ones increased significantly during the late Miocene. The reconstructed climate data indicates that high temperature and significantly low precipitation during the winter season (dry season) in the late Miocene might have enhanced forest fire which favoured the expansion of C4 plants over C3 plants during the period. This idea gets further support not only from a recent forest fire in northern India that was caused by the weakening of winter precipitation, but also from the burnt wood recovered from the late Miocene Siwalik sediments of northern India.

Tectonic Evolution of the Çayirhan Neogene Basin (Ankara), Central Turkey

NASA Astrophysics Data System (ADS)

Behzad, Bezhan; Koral, Hayrettin; İşb&idot; l, Duygu; Karaaǧa; ç, Serdal

2016-04-01

Çayırhan (Ankara) is located at crossroads of the Western Anatolian extensional region, analogous to the Basin and Range Province, and suture zone of the Neotethys-Ocean, which is locus of the North Anatolian Transform since the Late Miocene. To the north of Çayırhan (Ankara), a Neogene sedimentary basin comprises Lower-Middle Miocene and Upper Miocene age formations, characterized by swamp, fluvial and lacustrine settings respectively. This sequence is folded and transected by neotectonic faults. The Sekli thrust fault is older than the Lower-Middle Miocene age formations. The Davutoǧlan fault is younger than the Lower-Middle Miocene formations and is contemporaneous to the Upper Miocene formation. The Çatalkaya fault is younger than the Upper Miocene formation. The sedimentary and tectonic features provide information on mode, timing and evolution of this Neogene age sedimentary basin in Central Turkey. It is concluded that the region underwent a period of uplift and erosion under the influence of contractional tectonics prior to the Early-Middle Miocene, before becoming a semi-closed basin under influence of transtensional tectonics during the Early-Middle Miocene and under influence of predominantly extensional tectonics during the post-Late Miocene times. Keywords: Tectonics, Extension, Transtension, Stratigraphy, Neotectonic features.

Zooxanthellae of the Montastraea annularis species complex: patterns of distribution of four taxa of Symbiodinium on different reefs and across depths.

PubMed

Toller, W W; Rowan, R; Knowlton, N

2001-12-01

Corals of the Montastraea annularis complex host several different dinoflagellates in the genus Symbiodinium. Here we address two questions arising from our previous studies of these associations on an offshore reef. First, do the same taxa and patterns of association (Symbiodinium A and B found in higher irradiance habitats than Symbiodinium C) occur on an inshore reef? Second, does M. franksi at the limits of its depth range host only Symbiodinium C, as it does at intermediate depths? In both surveys, a new Symbiodinium taxon and different patterns of distribution (assayed by analyses of small ribosomal subunit RNA genes [srDNA]) were observed. Inshore, a taxon we name Symbiodinium E predominated in higher irradiance habitats in M. franksi and its two sibling species; the only other zooxanthella observed was Symbiodinium C. Offshore, M. franksi mainly hosted Symbiodinium C, but hosted Symbiodinium A, B, C, and E in shallow water and Symbiodinium E and C in very deep water. Symbiodinium E may be stress-tolerant. Observed srDNA heterogeneity within samples of Symbiodinium B, C, and E is interpreted as variation across copies within this multigene family. Experimental bleaching of Symbiodinium C supported this interpretation. Thus sequences from natural samples should be interpreted cautiously.

Episodic Disturbance from Boat Anchoring Is a Major Contributor to, but Does Not Alter the Trajectory of, Long-Term Coral Reef Decline

PubMed Central

Forrester, Graham E.; Flynn, Rebecca L.; Forrester, Linda M.; Jarecki, Lianna L.

2015-01-01

Isolating the relative effects of episodic disturbances and chronic stressors on long-term community change is challenging. We assessed the impact of an episodic disturbance associated with human visitation (boat anchoring) relative to other drivers of long-term change on coral reefs. A one-time anchoring event at Crab Cove, British Virgin Islands, in 2004 caused rapid losses of coral and reef structural complexity that were equal to the cumulative decline over 23 years observed at an adjacent site. The abundance of small site-attached reef fishes dropped by approximately one quarter after the anchoring event, but this drop was not immediate and only fully apparent two years after the anchoring event. There was no obvious recovery from the impact, and no evidence that this episodic impact accelerated or retarded subsequent declines from other causes. This apparent lack of synergism between the effect of this episodic human impact and other chronic stressors is consistent with the few other long-term studies of episodic impacts, and suggests that action to mitigate anchor damage should yield predictable benefits. PMID:26717208

Evolutionary history of the parrotfishes: biogeography, ecomorphology, and comparative diversity.

PubMed

Streelman, J T; Alfaro, M; Westneat, M W; Bellwood, D R; Karl, S A

2002-05-01

The family Scaridae comprises about 90 species of herbivorous coral reef, rock reef, and seagrass fishes. Parrotfishes are important agents of marine bioerosion who rework the substrate with their beaklike oral jaws. Many scarid populations are characterized by complex social systems including highly differentiated sexual stages, territoriality, and the defense of harems. Here, we test a hypothesis of relationships among parrotfish genera derived from nearly 2 kb of nuclear and mitochondrial DNA sequence. The DNA tree is different than a phylogeny based on comparative morphology and leads to important reinterpretations of scarid evolution. The molecular data suggest a split among seagrass and coral reef associated genera with nearly 80% of all species in the coral reef clade. Our phylogenetic results imply an East Tethyan origin of the family and the recurrent evolution of excavating and scraping feeding modes. It is likely that ecomorphological differences played a significant role in the initial divergence of major scarid lineages, but that variation in color and breeding behavior has triggered subsequent diversification. We present a two-phase model of parrotfish evolution to explain patterns of comparative diversity. Finally, we discuss the application of this model to other adaptively radiating clades.

Local phylogenetic divergence and global evolutionary convergence of skull function in reef fishes of the family Labridae.

PubMed

Westneat, Mark W; Alfaro, Michael E; Wainwright, Peter C; Bellwood, David R; Grubich, Justin R; Fessler, Jennifer L; Clements, Kendall D; Smith, Lydia L

2005-05-22

The Labridae is one of the most structurally and functionally diversified fish families on coral and rocky reefs around the world, providing a compelling system for examination of evolutionary patterns of functional change. Labrid fishes have evolved a diverse array of skull forms for feeding on prey ranging from molluscs, crustaceans, plankton, detritus, algae, coral and other fishes. The species richness and diversity of feeding ecology in the Labridae make this group a marine analogue to the cichlid fishes. Despite the importance of labrids to coastal reef ecology, we lack evolutionary analysis of feeding biomechanics among labrids. Here, we combine a molecular phylogeny of the Labridae with the biomechanics of skull function to reveal a broad pattern of repeated convergence in labrid feeding systems. Mechanically fast jaw systems have evolved independently at least 14 times from ancestors with forceful jaws. A repeated phylogenetic pattern of functional divergence in local regions of the labrid tree produces an emergent family-wide pattern of global convergence in jaw function. Divergence of close relatives, convergence among higher clades and several unusual 'breakthroughs' in skull function characterize the evolution of functional complexity in one of the most diverse groups of reef fishes.

Geologic Map of the Eastern Three-Quarters of the Cuyama 30' x 60' Quadrangle, California

USGS Publications Warehouse

Kellogg, Karl S.; Minor, Scott A.; Cossette, Pamela M.

2008-01-01

The map area encompasses a large part of the western Transverse Ranges and southern Coast Ranges of southern California. The San Andreas fault (SAF) cuts the northern part of the map. The area south of the SAF, about 80 percent of the map area, encompasses several distinct tectonic blocks bounded by major thrust or reverse faults, including the Santa Ynez fault, Big Pine fault (and structurally continuous Pine Mountain fault), Tule Creek fault, Nacimiento fault, Ozena fault, Munson Creek fault, Morales fault, and Frazier Mountain Thrust System. Movement on these faults is as old as Miocene and some faults may still be active. In addition, the Paleocene Sawmill Mountain Thrust south of the SAF and the Pastoria Thrust north of the SAF place Cretaceous and older crystalline rocks above Pelona Schist (south of the SAF) and Rand Schist (north of the SAF). South of the SAF, each tectonic block contains a unique stratigraphy, reflecting either large-scale movement on bounding faults or different depositional environments within each block. On Mount Pinos and Frazier Mountain, intrusive and metamorphic rocks as old as Mesoproterozoic, but including voluminous Cretaceous granitoid rocks, underlie or are thrust above non-marine sedimentary rocks as old as Miocene. Elsewhere, marine and non-marine sedimentary rocks are as old as Cretaceous, dominated by thick sequences of both Eocene and Cretaceous marine shales and sandstones. Middle Miocene to early Oligocene volcanic rocks crop out in the Caliente Hills (part of Caliente Formation) and south of Mount Pinos (part of the Plush Ranch Formation). Fault-bounded windows of Jurassic Franciscan Complex ophiolitic rocks are evident in the southwest corner of the area. North of the SAF, marine and non-marine sedimentary rocks as old as Eocene and Miocene volcanic rocks overlie a crystalline basement complex. Basement rocks include Cretaceous intrusive rocks that range from monzogranite to diorite, and Jurassic to late Paleozoic intrusive and metamorphic rocks. The Jurassic to late Paleozoic intrusive rocks include diorite, gabbro, and ultramafic rocks, and the metasedimentary rocks include marble, quartzite, schist, and gneiss.

Post-emplacement history of the Zambales Ophiolite Complex: Insights from petrography, geochronology and geochemistry of Neogene clastic rocks

NASA Astrophysics Data System (ADS)

Dimalanta, C. B.; Salapare, R. C.; Faustino-Eslava, D. V.; Ramos, N. T.; Queaño, K. L.; Yumul, G. P.; Yang, T. F.

2015-05-01

The Zambales Ophiolite Complex in Luzon, Philippines is made up of two blocks with differing geochemical signatures and ages - the Middle Jurassic to Early Cretaceous Acoje Block-San Antonio Massif that is of island arc tholeiite composition and the Eocene Coto Block-Cabangan Massif which is of transitional mid-ocean ridge basalt-island arc tholeiite affinity. These ophiolitic bodies are overlain by Miocene to Pliocene sedimentary units whose petrochemistry are reported here for the first time. Varying degrees of influences from ophiolitic detritus and from arc volcanic materials, as shown by petrography and indicator elements including Cr, Co and Ni, are observed in these sedimentary formations from north to south and from the oldest to the youngest. The Early to Middle Miocene Cabaluan Formation, whose outcrops are found to overlie only the Acoje Block, registers a more dominant ophiolitic signature as compared to the Late Miocene to Pliocene Santa Cruz Formation. The Santa Cruz Formation is generally characterized by fewer ophiolitic clasts and higher amounts of felsic components. Additionally, within this formation itself, a pronounced compositional change is observed relative to its spatial distribution. From the south to the north, an increase in ophiolitic components and a relative decrease in felsic signature is noted in units of the Santa Cruz Formation. It is therefore inferred that changes in the petrochemistry of rocks from the older Cabaluan to the younger Santa Cruz sedimentary formations record a decline in the influx of ophiolitic detritus or, conversely, the introduction of more diverse sediment sources as the deposition progressed. Detrital zircon U-Pb ages from the Santa Cruz Formation, with peaks at 46.73 ± 0.94 and 5.78 ± 0.13 Ma, reflects this change in provenance from the unroofing of an Early Eocene oceanic crust to fresh contributions from an active volcanic arc during the Late Miocene. The contrast in compositions of the southern and northern Santa Cruz Formation also indicates a closer proximity of the southern units to the source of these non-ophiolitic sources, which most likely corresponds to the Pliocene volcanoes of the West Luzon Arc.

Geologic controls on submarine slope failure along the central U.S. Atlantic margin: Insights from the Currituck Slide Complex

USGS Publications Warehouse

Hill, Jenna C.; Brothers, Daniel S.; Craig, Bradley K.; ten Brink, Uri S.; Chaytor, Jason D.; Flores, Claudia

2017-01-01

Multiple styles of failure, ranging from densely spaced, mass transport driven canyons to the large, slab-type slope failure of the Currituck Slide, characterize adjacent sections of the central U.S. Atlantic margin that appear to be defined by variations in geologic framework. Here we use regionally extensive, deep penetration multichannel seismic (MCS) profiles to reconstruct the influence of the antecedent margin physiography on sediment accumulation along the central U.S. Atlantic continental shelf-edge, slope, and uppermost rise from the Miocene to Present. These data are combined with high-resolution sparker MCS reflection profiles and multibeam bathymetry data across the Currituck Slide Complex. Pre-Neogene allostratigraphic horizons beneath the slope are generally characterized by low gradients and convex downslope profiles. This is followed by the development of thick, prograded deltaic clinoforms during the middle Miocene. Along-strike variations in morphology of a regional unconformity at the top of this middle Miocene unit appear to have set the stage for differing styles of mass transport along the margin. Areas north and south of the Currituck Slide are characterized by oblique margin morphology, defined by an angular shelf-edge and a relatively steep (> 8°), concave slope profile. Upper slope sediment bypass, closely spaced submarine canyons, and small, localized landslides confined to canyon heads and sidewalls characterize these sectors of the margin. In contrast, the Currituck region is defined by a sigmoidal geometry, with a rounded shelf-edge rollover and gentler slope gradient (< 6°). Thick (> 800 m), regionally continuous stratified slope deposits suggest the low gradient Currituck region was a primary depocenter for fluvial inputs during multiple sea level lowstands. These results imply that the rounded, gentle slope physiography developed during the middle Miocene allowed for a relatively high rate of subsequent sediment accumulation, thus providing a mechanism for compaction–induced overpressure that preconditioned the Currituck region for failure. Detailed examination of the regional geological framework illustrates the importance of both sediment supply and antecedent slope physiography in the development of large, potentially unstable depocenters along passive margins.

Meteoric water circulation and rolling-hinge detachment faulting: Example of the Northern Snake Range core complex, Nevada

NASA Astrophysics Data System (ADS)

Gébelin, Aude; Teyssier, Christian; Heizler, Matthew T.; Andreas, Mulch

2014-05-01

The Northern Snake Range metamorphic core complex developed as a consequence of Oligo-Miocene extension of the Basin and Range Province and is bounded by an arched detachment that separates the cold, brittle upper crust from the ductile middle crust. On the western and eastern limbs of the arch, the detachment footwall displays continuous sections of muscovite-bearing quartzite and schist from which we report new microfabrics, δD values, and 40Ar/39Ar ages. Results indicate that the two limbs record distinct stages of the metamorphic and kinematic Cenozoic events, including Eocene collapse of previously overthickned crust in the west, and one main Oligo-Miocene extensional event in the east. Quartzite from the western part of the range preserves Eocene fabrics (~49-45 Ma) that developed during coaxial deformation in the presence of metamorphic fluids. In contrast, those from the east reveal a large component of non coaxial strain, Oligo-Miocene ages (27-21 Ma) and contain recrystallized muscovite grains indicating that meteoric fluids sourced at high elevation (low-δD) infiltrated the brittle-ductile transition zone during deformation. Percolation of meteoric fluids down to the mylonitic detachment footwall was made possible by the development of an east-dipping rolling-hinge detachment system that controlled the timing and location of active faulting in the brittle upper crust and therefore the pathway of fluids from the surface to the brittle-ductile transition. Oligo-Miocene upper crustal extension was accommodated by a fan-shaped fault pattern that generated shear and tension fractures and channelized surface fluids, while top-to-the-east ductile shearing and advection of hot material in the lower plate allowed the system to be progressively exhumed. As extension proceeded, brittle normal faults active in the wedge of the hanging wall gradually rotated and translated above the detachment fault where, became inactive and precluded the circulation of fluids from the surface to the lower plate. The Eocene section observed on the western limb represents an example of such a tilted block that was rotated and exhumed in the first stages of the rolling-hinge detachment activity.

Evolution of seismically active İzmir-Balıkesir Transfer Zone: A reactivated and deep-seated structure since the Miocene

NASA Astrophysics Data System (ADS)

Uzel, Bora; Sözbilir, Hasan; Kaymakci, Nuretdin; Özkaymak, Caglar; Ozkaptan, Murat; Ay, Selin; Langereis, Cornelis G.

2017-04-01

Within the Aegean extensional system, the İzmir-Balikesir Transfer Zone (İBTZ) is a recently recognized structure that have played important role in the late Cenozoic evolution of western Anatolia by accommodating the differential deformation between the Cycladic (CCC) and the Menderes (MCC) metamorphic core complexes. There is wealth of information about the transform nature of the zone during the late Cretaceous. Some of the faults within the İBTZ have earliest record of their activity in the late Cretaceous related to closure of the Neotethys. In this contribution we will present; (i) the vertical axis rotational history of western Anatolia using paleomagnetic data from the Miocene volcano-sedimentary rocks, (ii) kinematics of the major faults based on fault slip analysis of, and (iii) focal mechanism solutions of the recent seismic activity to better understand the İBTZ since the Miocene. Paleomagnetic results reveal two discrete and opposite major rotational phases since the early Miocene. Kinematics of structures agrees with these results while three major deformational phases are identified along the İBTZ. The focal mechanism solutions of recent seismic events -such as 1992 Doǧanbey, 2003 Seferihisar and 2005 Sıǧacık earthquakes- occurred along the İBTZ corroborate that it is still an active structure and transfers west Anatolian extensional strain into the Aegean Sea. Combining mantle tomography, paleomagnetic, kinematic, and seismic activity along the zone suggests that the İBTZ is not only links two core complexes, the MCC and the CCC, but also corresponds to a deep-seated structure related to a tear along the subducted northern edge of the African slab. Hence, it is not only a surface expression of a tear in the subducting African slab, but also one of the main seismic sources of the region. This work is supported by the Scientific and Technical Research Council of Turkey (TÜBİTAK) research grant of ÇAYDAǧ-109Y044 and partly by the Dokuz Eylül University Scientific Research (BAP) Project: 2007.KB.FEN.039.

Long-term landscape evolution of the Basal Complexes of Fuerteventura and La Gomera Islands, Canary Archipelago

NASA Astrophysics Data System (ADS)

Mansour, Sherif; Glasmacher, Ulrich A.; Albinger, Marie; Stoeckli, Daniel F.

2014-05-01

The Canarias archipelago consists from seven volcanic islands located at the northwestern African margin. Among them only Fuerteventura and La Gomera islands show distinctive wide exposures of the basal complex (BC) that is characteristic with complex geological history. The basal complex was exposed on the western part of Fuerteventura and northwestern sector of La Gomera because of giant landslide(s) which have removed most of the shield stage volcanic rocks (Ancochea et al., 1996; 2006; Stillman, 1999). Generally, landslides are a common feature in the earlier constructive stages of the entire archipelago and many other volcanic islands (McGuire, 1996). Integration of low temperature thermochronological data, and time-Temperature (t-T) numerical modelling have proven to be a powerful tool for reconstructing the thermal and tectonic history, defining and quantifying long-term landscape evolution in variety of geological settings. Therefore, zircon and apatite fission-track techniques and t-T paths modelling were applied to 36 samples representing the main rock units of the BC on both islands. Fuerteventura BC has experienced two very rapid cooling/exhumation events. While, La Gomera BC shows one long-lived very fast cooling/exhumation event. Interestingly, these very rapid cooling/exhumation events are synchronous with these major landslides. There are many reasons for the major landslides on such a volcanic island (see e.g. McGuire, 1996)., But, the most sufficient triggers for these huge mass wasting/landslides events on Fuerteventura and La Gomera are recommended to be the continuous igneous intrusions and dikes which have the potential to decrease the edifice stability, igneous extrusions which add new materials at the surface leading to over-steeping and overloading (McGuire, 1996), and major climatic changes of the Middle Miocene Climatic Optimum (Herold et al., 2011). References Ancochea, E., Brändle, J.L., Cubas, C.R.,Hernán, F.,Huertas, M.J., 1996. Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the Island of Fuerteventura. Journal of Volcanology and Geothermal Research 70, 183-204. Ancochea, E., Hernán, F., Huertas, M.J., Brändle, J.L., Herrera, R., 2006. A new chronostratigraphical and evolutionary model for La Gomera: implications for the overall evolution of the Canarian Archipelago. Journal of Volcanology and Geothermal Research 157, 271-293. Herold, N., Huber, M., Greenwood, D.R., Müller, R.D., Seton, M., 2011. Early to Middle Miocene monsoon climate in Australia. Geology 39, 3-6. McGuire, W.J., 1996. Volcano instability: a review of contemporary themes. In: McGuire, W.J., Jones, A.P., Neuberg, J. (Eds.), Volcano Instability on the Earth and Terrestrial Planets. Geological Society of London, Special Publication 110, 1-23. Stillman, C.J., 1999. Giant Miocene landslides and the evolution of Fuerteventura, Canary Islands. Journal of Volcanology and Geothermal Research 94, 89-104.

An integrated study on microtectonics, geothermometry and thermochronology of the Çataldaǧ Core Complex (NW Turkey): Implications for cooling, deformation and uplift history

NASA Astrophysics Data System (ADS)

Kamaci, Omer; Altunkaynak, Safak

2017-04-01

We present an integrated study on structure, microstructure, geothermometry and thermochronology of the Çataldaǧ Core Complex (ÇCC) in NW Turkey in order to understand the cooling, deformation and uplift mechanisms. ÇCC is formed from an Eo-Oligocene granite-gneiss-migmatite complex (GGMC) and an Early Miocene I-type granodioritic body (ÇG: Çataldaǧ granodiorite) which were exhumed as a dome-shaped core complex in the footwall of a ring-shaped low-angle detachment zone (The Çataldaǧ Detachment Fault Zone; ÇDFZ) in the Early Miocene. New U-Pb zircon (LA-ICPMS) and monazite ages of GGMC yielded magmatic ages of 33.8 and 30.1 Ma (Latest Eocene-Early Oligocene). 40Ar/39Ar muscovite, biotite and K-feldspar from the GGMC yielded the deformation age span 21.38±0,05 Ma and 20.81±0.04 Ma, which is also the emplacement age (20.84±0.13 Ma and 21.6±0.04 Ma) of ÇG. ÇDFZ is responsible for mainly top-to-the-north sense kinematic processes. The microstructural features of quartz, feldspar and mica indicate that the ÇCC has undergone continuous deformations during its cooling, from submagmatic to cataclastic conditions. Five microstructural grades have been classified under ductile (DZ) and ductile-to-brittle shear zone (SZ), according to the estimated deformation temperature and intensity of the strain. Microcline twinning, marginally replacement myrmekite and flame-perthite are predominant features for feldspar while chessboard extinction, grain boundary migration and subgrain rotation recrystallization is common for quartz in the DZ which has a deformation temperature range of >600°C to 400°C. Grain size reduction is an important factor for the ductile to brittle shear zone (SZ). Feldspar is represented by bulging recrystallization (BLG), feldspar-fish and domino-type microfracture/microfaulting and quartz show more elongated structures such as ribbons with high aspect ratios. Mineral-fish (muscovite, biotite and feldspar) structures indicate a temperature range of 500°C to <250°C. The GGMC and ÇG, which were formed in different periods, suffered continuous ductile-to-brittle deformation and uplifted together along ÇDFZ during Early Miocene when the first major period of N-S extension began in the western Anatolia. Microstructural grades, two-feldspar geothermometry and geochronological data indicate that the GGMC and ÇG, which were formed in different periods, suffered continuous ductile-to-brittle deformation and uplifted together along ÇDFZ during Early Miocene when the first major period of N-S extension began in the western Anatolia.

Miocene leaves of Elaeagnus (Elaeagnaceae) from the Qinghai-Tibet Plateau, its modern center of diversity and endemism.

PubMed

Su, Tao; Wilf, Peter; Xu, He; Zhou, Zhe-Kun

2014-08-01

• The Qinghai-Tibet Plateau is a major center of plant diversity and endemism, but little is known about how this developed due to the region's very scarce paleobotanical record. The silverberry genus Elaeagnus (Elaeagnaceae) reaches its greatest diversity (54 species) and endemism (36 species) in this area. Fossil Elaeagnaceae could provide significant evidence for the phylogeny and biogeography of the family and contribute primary data regarding the evolution of the unique Qinghai-Tibet Plateau flora in its dramatic setting of tectonic and climatic change.• We describe four fossil leaves with diagnostic features of Elaeagnus from the late Miocene of eastern Tibet, modern altitude of 3910 m a.s.l.. We also review prior fossil records of Elaeagnaceae.• The well-preserved, densely packed, stellate scales on fossil leaf surfaces are diagnostic of Elaeagnaceae. We assign these fossil leaves to Elaeagnus tibetensis T. Su et Z.K. Zhou sp. nov., comprising the first confirmed fossil Elaeagnus leaves worldwide.• Elaeagnus was present in eastern Tibet by the late Miocene. Together with previous fossil records, the new species supports a Holarctic history of the family. The diversification of Elaeagnus in the Qinghai-Tibet Plateau and adjacent areas might have been driven by continuous uplift at least since the late Miocene, causing formation of complex topography and climate with high rainfall seasonality. The characteristic scales on leaf surfaces are likely to be an important functional adaptation to seasonal droughts during early spring. © 2014 Botanical Society of America, Inc.

Geologic map of the East of Grotto Hills Quadrangle, California: a digital database

USGS Publications Warehouse

Nielson, Jane E.; Bedford, David R.

1999-01-01

The East of Grotto Hills 1:24,000-scale quadrangle of California lies west of the Colorado River about 30 km southwest of Searchlight, Nevada, near the boundary between the northern and southern parts of the Basin and Range Province. The quadrangle includes the eastern margin of Lanfair Valley, the southernmost part of the Castle Mountains, and part of the northwest Piute Range. The generally north-trending Piute Range aligns with the Piute and Dead Mountains of California and the Newberry and Eldorado Mountains and McCullough Range of Nevada. The southern part of the Piute Range adjoins Homer Mountain (Spencer and Turner, 1985) near Civil War-era Fort Piute. Adjacent 1:24,000-scale quadrangles include Castle Peaks, Homer Mountain, and Signal Hill, Calif.; also Hart Peak, Tenmile Well, and West of Juniper Mine, Calif. and Nev. The mapped area contains Tertiary (Miocene) volcanic and sedimentary rocks, interbedded with and overlain by Tertiary and Quaternary surficial deposits. Miocene intrusions mark conduits that served as feeders for the Miocene volcanic rocks, which also contain late magma pulses that cut the volcanic section. Upper Miocene conglomerate deposits interfinger with the uppermost volcanic flows. Canyons and intermontane valleys contain dissected Quaternary alluvial-fan deposits, mantled by active alluvial-fan deposits and detritus of active drainages. The alluvial materials were derived largely from Early Proterozoic granite and gneiss complexes, intruded by Mesozoic granite, dominate the heads of Lanfair Valley drainages in the New York Mountains and Mid Hills (fig. 1; Jennings, 1961). Similar rocks also underlie Tertiary deposits in the Castle Peaks, Castle Mountains, and eastern Piute Range.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wayne Pennington; Mohamed Ibrahim; Roger Turpening

Crosswell seismic surveys were conducted at two fields in northern Michigan. One of these, Springdale, included two monitor wells that are located external to the reef, and the other, Coldspring, employed two production wells within the reef. The Springdale wells extended to much greater depths than the reef, and imaging was conducted from above and from beneath the reef. The resulting seismic images provide the best views of pinnacle Niagaran reefs obtained to date. The tops of the reservoirs can be clearly distinguished, and their lateral extent or dipping edges can be observed along the profile. Reflecting events internal tomore » the reef are evident; some of them are fairly continuous across the reef and others are discontinuous. Inversion of the seismic data indicates which events represent zones of higher porosity and which are lower porosity or even anhydrite plugged. The full stacked image includes angles that are beyond critical for many of the interfaces, and some reflections are visible only for a small range of angles, presumably near their critical angle. Stacking these angles in provides an opportunity for these events to be seen on the stacked image, where otherwise they would have been unrecognized. For inversion, however, the complexity associated with phase changes beyond critical can lead to poor results, and elastic inversion of partial angle stacks may be best conducted with restrictions to angles less than critical. Strong apparent attenuation of signals occurs when seismic ray paths pass through the upper part of the Springdale reservoir; this may be due to intrinsic attenuation and/or scattering of events due to the locally strongly varying gas saturation and extremely low fluid pressures. Signal-to-noise limitations become evident far from the source well in the Coldspring study, probably because the raw data were strongly affected by tube-wave noise generated by flow through the perforation of the receiver well. The seismic images obtained, and interpretations of them, as assisted by Amplitude-versus-Angle studies and accompanying inversion, provide additional insight into the internal geometry of these two reefs and provide data that should be useful for reservoir management.« less

Non-Random Variability in Functional Composition of Coral Reef Fish Communities along an Environmental Gradient.

PubMed

Plass-Johnson, Jeremiah G; Taylor, Marc H; Husain, Aidah A A; Teichberg, Mirta C; Ferse, Sebastian C A

2016-01-01

Changes in the coral reef complex can affect predator-prey relationships, resource availability and niche utilisation in the associated fish community, which may be reflected in decreased stability of the functional traits present in a community. This is because particular traits may be favoured by a changing environment, or by habitat degradation. Furthermore, other traits can be selected against because degradation can relax the association between fishes and benthic habitat. We characterised six important ecological traits for fish species occurring at seven sites across a disturbed coral reef archipelago in Indonesia, where reefs have been exposed to eutrophication and destructive fishing practices for decades. Functional diversity was assessed using two complementary indices (FRic and RaoQ) and correlated to important environmental factors (live coral cover and rugosity, representing local reef health, and distance from shore, representing a cross-shelf environmental gradient). Indices were examined for both a change in their mean, as well as temporal (short-term; hours) and spatial (cross-shelf) variability, to assess whether fish-habitat association became relaxed along with habitat degradation. Furthermore, variability in individual traits was examined to identify the traits that are most affected by habitat change. Increases in the general reef health indicators, live coral cover and rugosity (correlated with distance from the mainland), were associated with decreases in the variability of functional diversity and with community-level changes in the abundance of several traits (notably home range size, maximum length, microalgae, detritus and small invertebrate feeding and reproductive turnover). A decrease in coral cover increased variability of RaoQ while rugosity and distance both inversely affected variability of FRic; however, averages for these indices did not reveal patterns associated with the environment. These results suggest that increased degradation of coral reefs is associated with increased variability in fish community functional composition resulting from selective impacts on specific traits, thereby affecting the functional response of these communities to increasing perturbations.

Cross-shore velocity shear, eddies and heterogeneity in water column properties over fringing coral reefs: West Maui, Hawaii

USGS Publications Warehouse

Storlazzi, C.D.; McManus, M.A.; Logan, J.B.; McLaughlin, B.E.

2006-01-01

A multi-day hydrographic survey cruise was conducted to acquire spatially extensive, but temporally limited, high-resolution, three-dimensional measurements of currents, temperature, salinity and turbidity off West Maui in the summer of 2003 to better understand coastal dynamics along a complex island shoreline with coral reefs. These data complement long-term, high-resolution tide, wave, current, temperature, salinity and turbidity measurements made at a number of fixed locations in the study area starting in 2001. Analyses of these hydrographic data, in conjunction with numerous field observations, evoke the following conceptual model of water and turbidity flux along West Maui. Wave- and wind-driven flows appear to be the primary control on flow over shallower portions of the reefs while tidal and subtidal currents dominate flow over the outer portions of the reefs and insular shelf. When the direction of these flows counter one another, which is quite common, they cause a zone of cross-shore horizontal shear and often form a front, with turbid, lower-salinity water inshore of the front and clear, higher-salinity water offshore of the front. It is not clear whether these zones of high shear and fronts are the cause or the result of the location of the fore reef, but they appear to be correlated alongshore over relatively large horizontal distances (orders of kilometers). When two flows converge or when a single flow is bathymetrically steered, eddies can be generated that, in the absence of large ocean surface waves, tend to accumulate material. Areas of higher turbidity and lower salinity tend to correlate with regions of poor coral health or the absence of well-developed reefs, suggesting that the oceanographic processes that concentrate and/or transport nutrients, contaminants, low-salinity water or suspended sediment might strongly influence coral reef ecosystem health and sustainability.

Disease outbreaks, bleaching and a cyclone drive changes in coral assemblages on an inshore reef of the Great Barrier Reef

NASA Astrophysics Data System (ADS)

Haapkylä, J.; Melbourne-Thomas, J.; Flavell, M.; Willis, B. L.

2013-09-01

Coral disease is a major threat to the resilience of coral reefs; thus, understanding linkages between disease outbreaks and disturbances predicted to increase with climate change is becoming increasingly important. Coral disease surveys conducted twice yearly between 2008 and 2011 at a turbid inshore reef in the central Great Barrier Reef spanned two disturbance events, a coral bleaching event in 2009 and a severe cyclone (cyclone `Yasi') in 2011. Surveys of coral cover, community structure and disease prevalence throughout this 4-yr study provide a unique opportunity to explore cumulative impacts of disturbance events and disease for inshore coral assemblages. The principal coral disease at the study site was atramentous necrosis (AtN), and it primarily affected the key inshore, reef-building coral Montipora aequituberculata. Other diseases detected were growth anomalies, white syndrome and brown band syndrome. Diseases affected eight coral genera, although Montipora was, by far, the genus mostly affected. The prevalence of AtN followed a clear seasonal pattern, with disease outbreaks occurring only in wet seasons. Mean prevalence of AtN on Montipora spp. (63.8 % ± 3.03) was three- to tenfold greater in the wet season of 2009, which coincided with the 2009 bleaching event, than in other years. Persistent wet season outbreaks of AtN combined with the impacts of bleaching and cyclone events resulted in a 50-80 % proportional decline in total coral cover. The greatest losses of branching and tabular acroporids occurred following the low-salinity-induced bleaching event of 2009, and the greatest losses of laminar montiporids occurred following AtN outbreaks in 2009 and in 2011 following cyclone Yasi. The shift to a less diverse coral assemblage and the concomitant loss of structural complexity are likely to have long-term consequences for associated vertebrate and invertebrate communities on Magnetic Island reefs.

Temporal and taxonomic contrasts in coral growth at Davies Reef, central Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

Anderson, Kristen D.; Cantin, Neal E.; Heron, Scott F.; Lough, Janice M.; Pratchett, Morgan S.

2018-06-01

Demographic processes, such as growth, can have an important influence on the population and community structure of reef-building corals. Importantly, ongoing changes in environmental conditions (e.g. ocean warming) are expected to affect coral growth, contributing to changes in the structure of coral populations and communities. This study quantified contemporary growth rates (linear extension and calcification) for the staghorn coral, Acropora muricata, at Davies Reef, central Great Barrier Reef, Australia. Growth rates were measured at three different depths (5, 10, and 15 m) over 2 yr (2012-2014) assessing both seasonal and inter-annual variability. Results of this study were compared to equivalent measurements made in 1980-1982 at the same location. To assist in understanding inter-annual variability in coral growth, we also examined annual growth bands from massive Porites providing continuous growth and records of flooding history for Davies Reef over the period 1979-2012. Linear extension rates of A. muricata were substantially (11-62%) lower in 2012-2014 compared to 1980-1982, especially at 10 and 15 m depths. These declines in growth coincide with a + 0.14 °C change in annual mean temperature. For massive Porites, however, calcification rates were highly variable among years and there was no discernible long-term change in growth despite sustained increases in temperature of 0.064 °C per decade. Apparent differences in the growth rates of Acropora between 1980-1982 and 2012-2014 may reflect inter-annual variation in coral growth (as seen for massive Porites), though it is known branching Acropora is much more sensitive to changing environmental conditions than massive corals. There are persistent issues in assessing the sensitivities of branching corals to environmental change due to limited capacity for retrospective analyses of growth, but given their disproportionate contribution to habitat complexity and reef structure, it is critical to ascertain whether there are increasing impacts on their demography.

Non-Random Variability in Functional Composition of Coral Reef Fish Communities along an Environmental Gradient

PubMed Central

Plass-Johnson, Jeremiah G.; Taylor, Marc H.; Husain, Aidah A. A.; Teichberg, Mirta C.; Ferse, Sebastian C. A.

2016-01-01

Changes in the coral reef complex can affect predator-prey relationships, resource availability and niche utilisation in the associated fish community, which may be reflected in decreased stability of the functional traits present in a community. This is because particular traits may be favoured by a changing environment, or by habitat degradation. Furthermore, other traits can be selected against because degradation can relax the association between fishes and benthic habitat. We characterised six important ecological traits for fish species occurring at seven sites across a disturbed coral reef archipelago in Indonesia, where reefs have been exposed to eutrophication and destructive fishing practices for decades. Functional diversity was assessed using two complementary indices (FRic and RaoQ) and correlated to important environmental factors (live coral cover and rugosity, representing local reef health, and distance from shore, representing a cross-shelf environmental gradient). Indices were examined for both a change in their mean, as well as temporal (short-term; hours) and spatial (cross-shelf) variability, to assess whether fish-habitat association became relaxed along with habitat degradation. Furthermore, variability in individual traits was examined to identify the traits that are most affected by habitat change. Increases in the general reef health indicators, live coral cover and rugosity (correlated with distance from the mainland), were associated with decreases in the variability of functional diversity and with community-level changes in the abundance of several traits (notably home range size, maximum length, microalgae, detritus and small invertebrate feeding and reproductive turnover). A decrease in coral cover increased variability of RaoQ while rugosity and distance both inversely affected variability of FRic; however, averages for these indices did not reveal patterns associated with the environment. These results suggest that increased degradation of coral reefs is associated with increased variability in fish community functional composition resulting from selective impacts on specific traits, thereby affecting the functional response of these communities to increasing perturbations. PMID:27100189

Scale-invariance of sediment patterns - the fingerprint of fundamental drivers (Jean Baptiste Lamarck Medal Lecture)

NASA Astrophysics Data System (ADS)

Schlager, Wolfgang

2015-04-01

In contrast to the realms of magmatism and metamorphism, most depositional processes can be observed directly at the earth's surface. Observation of sediment patterns advanced significantly with the advent of remote sensing and 3D reflection seismics. Remote sensing is particularly relevant for the present topic because it documents mainly Holocene sediments - the best objects to link depositional processes to products. Classic examples of scale-invariant geometry are channel-fan systems, i.e. river-delta and canyon-fan complexes. The underlying control in both instances is the energy-dispersion of a channeled stream of water that discharges in a body of still water. The resulting fan-shaped sediment accumulations are scale-invariant over 7 orders of magnitude in linear size. The Mesozoic-Cenozoic record shows comparable trends and patterns. Further examples of depositional scale-invariance include foresets of non-cohesive sediments and braided-channel deposits. Reefs and carbonate platforms offer an example of scale-invariance related to biotic growth. Shallow-water carbonate platforms rimmed by reefs or reef-rimmed atolls with deep lagoons are characteristic morphologies of tropical carbonate deposits. The structure has been compared to a bucket where stiff reef rims hold a pile of loose sediment. Remote sensing data from the Maldive, Chagos and Laccadive archipelagos of the Indian Ocean show that bucket structures are the dominant depositional pattern from meter-size reefs to archipelagos of hundreds of kilometers in diameter, i.e. over more than 4 orders of magnitude in linear size. Over 2.5 orders of magnitude, the bucket structures qualify as statistical fractals. Ecologic and hydrodynamic studies on modern reefs suggest that the bucket structure is a form of biotic self-organization: The edge position in a reef is favored over the center position because bottom shear is higher and the diffusive boundary layer between reef and water thinner. Thus, the reef edge has easier access to nutrients. Moreover, the edge is less likely to be buried by sediment. The bucket structure is an ecologic response to these conditions. Buckets have been documented from all periods of the Phanerozoic and analogous structures from the late Proterozoic show that the microbial carbonate factory also built buckets. We conclude that a voyage through scales in the sediment realm reveals islands of scale-invariance wherever a single principle dominates the sedimentation process.

Elevated Colonization of Microborers at a Volcanically Acidified Coral Reef

PubMed Central

Enochs, Ian C.; Manzello, Derek P.; Tribollet, Aline; Valentino, Lauren; Kolodziej, Graham; Donham, Emily M.; Fitchett, Mark D.; Carlton, Renee; Price, Nichole N.

2016-01-01

Experiments have demonstrated that ocean acidification (OA) conditions projected to occur by the end of the century will slow the calcification of numerous coral species and accelerate the biological erosion of reef habitats (bioerosion). Microborers, which bore holes less than 100 μm diameter, are one of the most pervasive agents of bioerosion and are present throughout all calcium carbonate substrates within the reef environment. The response of diverse reef functional groups to OA is known from real-world ecosystems, but to date our understanding of the relationship between ocean pH and carbonate dissolution by microborers is limited to controlled laboratory experiments. Here we examine the settlement of microborers to pure mineral calcium carbonate substrates (calcite) along a natural pH gradient at a volcanically acidified reef at Maug, Commonwealth of the Northern Mariana Islands (CNMI). Colonization of pioneer microborers was higher in the lower pH waters near the vent field. Depth of microborer penetration was highly variable both among and within sites (4.2–195.5 μm) over the short duration of the study (3 mo.) and no clear relationship to increasing CO2 was observed. Calculated rates of biogenic dissolution, however, were highest at the two sites closer to the vent and were not significantly different from each other. These data represent the first evidence of OA-enhancement of microboring flora colonization in newly available substrates and provide further evidence that microborers, especially bioeroding chlorophytes, respond positively to low pH. The accelerated breakdown and dissolution of reef framework structures with OA will likely lead to declines in structural complexity and integrity, as well as possible loss of essential habitat. PMID:27467570

Elevated Colonization of Microborers at a Volcanically Acidified Coral Reef.

PubMed

Enochs, Ian C; Manzello, Derek P; Tribollet, Aline; Valentino, Lauren; Kolodziej, Graham; Donham, Emily M; Fitchett, Mark D; Carlton, Renee; Price, Nichole N

2016-01-01

Experiments have demonstrated that ocean acidification (OA) conditions projected to occur by the end of the century will slow the calcification of numerous coral species and accelerate the biological erosion of reef habitats (bioerosion). Microborers, which bore holes less than 100 μm diameter, are one of the most pervasive agents of bioerosion and are present throughout all calcium carbonate substrates within the reef environment. The response of diverse reef functional groups to OA is known from real-world ecosystems, but to date our understanding of the relationship between ocean pH and carbonate dissolution by microborers is limited to controlled laboratory experiments. Here we examine the settlement of microborers to pure mineral calcium carbonate substrates (calcite) along a natural pH gradient at a volcanically acidified reef at Maug, Commonwealth of the Northern Mariana Islands (CNMI). Colonization of pioneer microborers was higher in the lower pH waters near the vent field. Depth of microborer penetration was highly variable both among and within sites (4.2-195.5 μm) over the short duration of the study (3 mo.) and no clear relationship to increasing CO2 was observed. Calculated rates of biogenic dissolution, however, were highest at the two sites closer to the vent and were not significantly different from each other. These data represent the first evidence of OA-enhancement of microboring flora colonization in newly available substrates and provide further evidence that microborers, especially bioeroding chlorophytes, respond positively to low pH. The accelerated breakdown and dissolution of reef framework structures with OA will likely lead to declines in structural complexity and integrity, as well as possible loss of essential habitat.

Large-scale patterns of benthic marine communities in the Brazilian Province.

PubMed

Aued, Anaide W; Smith, Franz; Quimbayo, Juan P; Cândido, Davi V; Longo, Guilherme O; Ferreira, Carlos E L; Witman, Jon D; Floeter, Sergio R; Segal, Bárbara

2018-01-01

As marine ecosystems are influenced by global and regional processes, standardized information on community structure has become crucial for assessing broad-scale responses to natural and anthropogenic disturbances. Extensive biogeographic provinces, such as the Brazilian Province in the southwest Atlantic, present numerous theoretical and methodological challenges for understanding community patterns on a macroecological scale. In particular, the Brazilian Province is composed of a complex system of heterogeneous reefs and a few offshore islands, with contrasting histories and geophysical-chemical environments. Despite the large extent of the Brazilian Province (almost 8,000 kilometers), most studies of shallow benthic communities are qualitative surveys and/or have been geographically restricted. We quantified community structure of shallow reef habitats from 0° to 27°S latitude using a standard photographic quadrat technique. Percent cover data indicated that benthic communities of Brazilian reefs were dominated by algal turfs and frondose macroalgae, with low percent cover of reef-building corals. Community composition differed significantly among localities, mostly because of their macroalgal abundance, despite reef type or geographic region, with no evident latitudinal pattern. Benthic diversity was lower in the tropics, contrary to the general latitudinal diversity gradient pattern. Richness peaked at mid-latitudes, between 20°S to 23°S, where it was ~3.5-fold higher than localities with the lowest richness. This study provides the first large-scale description of benthic communities along the southwestern Atlantic, providing a baseline for macroecological comparisons and evaluation of future impacts. Moreover, the new understanding of richness distribution along Brazilian reefs will contribute to conservation planning efforts, such as management strategies and the spatial prioritization for the creation of new marine protected areas.

Habitat dynamics, marine reserve status, and the decline and recovery of coral reef fish communities.

PubMed

Williamson, David H; Ceccarelli, Daniela M; Evans, Richard D; Jones, Geoffrey P; Russ, Garry R

2014-02-01

Severe climatic disturbance events often have major impacts on coral reef communities, generating cycles of decline and recovery, and in some extreme cases, community-level phase shifts from coral-to algal-dominated states. Benthic habitat changes directly affect reef fish communities, with low coral cover usually associated with low fish diversity and abundance. No-take marine reserves (NTRs) are widely advocated for conserving biodiversity and enhancing the sustainability of exploited fish populations. Numerous studies have documented positive ecological and socio-economic benefits of NTRs; however, the ability of NTRs to ameliorate the effects of acute disturbances on coral reefs has seldom been investigated. Here, we test these factors by tracking the dynamics of benthic and fish communities, including the important fishery species, coral trout (Plectropomus spp.), over 8 years in both NTRs and fished areas in the Keppel Island group, Great Barrier Reef, Australia. Two major disturbances impacted the reefs during the monitoring period, a coral bleaching event in 2006 and a freshwater flood plume in 2011. Both disturbances generated significant declines in coral cover and habitat complexity, with subsequent declines in fish abundance and diversity, and pronounced shifts in fish assemblage structure. Coral trout density also declined in response to the loss of live coral, however, the approximately 2:1 density ratio between NTRs and fished zones was maintained over time. The only post-disturbance refuges for coral trout spawning stocks were within the NTRs that escaped the worst effects of the disturbances. Although NTRs had little discernible effect on the temporal dynamics of benthic or fish communities, it was evident that the post-disturbance refuges for coral trout spawning stocks within some NTRs may be critically important to regional-scale population persistence and recovery.

Large-scale patterns of benthic marine communities in the Brazilian Province

PubMed Central

Smith, Franz; Quimbayo, Juan P.; Cândido, Davi V.; Longo, Guilherme O.; Ferreira, Carlos E. L.; Witman, Jon D.; Floeter, Sergio R.; Segal, Bárbara

2018-01-01

As marine ecosystems are influenced by global and regional processes, standardized information on community structure has become crucial for assessing broad-scale responses to natural and anthropogenic disturbances. Extensive biogeographic provinces, such as the Brazilian Province in the southwest Atlantic, present numerous theoretical and methodological challenges for understanding community patterns on a macroecological scale. In particular, the Brazilian Province is composed of a complex system of heterogeneous reefs and a few offshore islands, with contrasting histories and geophysical-chemical environments. Despite the large extent of the Brazilian Province (almost 8,000 kilometers), most studies of shallow benthic communities are qualitative surveys and/or have been geographically restricted. We quantified community structure of shallow reef habitats from 0° to 27°S latitude using a standard photographic quadrat technique. Percent cover data indicated that benthic communities of Brazilian reefs were dominated by algal turfs and frondose macroalgae, with low percent cover of reef-building corals. Community composition differed significantly among localities, mostly because of their macroalgal abundance, despite reef type or geographic region, with no evident latitudinal pattern. Benthic diversity was lower in the tropics, contrary to the general latitudinal diversity gradient pattern. Richness peaked at mid-latitudes, between 20°S to 23°S, where it was ~3.5-fold higher than localities with the lowest richness. This study provides the first large-scale description of benthic communities along the southwestern Atlantic, providing a baseline for macroecological comparisons and evaluation of future impacts. Moreover, the new understanding of richness distribution along Brazilian reefs will contribute to conservation planning efforts, such as management strategies and the spatial prioritization for the creation of new marine protected areas. PMID:29883496

Habitat dynamics, marine reserve status, and the decline and recovery of coral reef fish communities

PubMed Central

Williamson, David H; Ceccarelli, Daniela M; Evans, Richard D; Jones, Geoffrey P; Russ, Garry R

2014-01-01

Severe climatic disturbance events often have major impacts on coral reef communities, generating cycles of decline and recovery, and in some extreme cases, community-level phase shifts from coral-to algal-dominated states. Benthic habitat changes directly affect reef fish communities, with low coral cover usually associated with low fish diversity and abundance. No-take marine reserves (NTRs) are widely advocated for conserving biodiversity and enhancing the sustainability of exploited fish populations. Numerous studies have documented positive ecological and socio-economic benefits of NTRs; however, the ability of NTRs to ameliorate the effects of acute disturbances on coral reefs has seldom been investigated. Here, we test these factors by tracking the dynamics of benthic and fish communities, including the important fishery species, coral trout (Plectropomus spp.), over 8 years in both NTRs and fished areas in the Keppel Island group, Great Barrier Reef, Australia. Two major disturbances impacted the reefs during the monitoring period, a coral bleaching event in 2006 and a freshwater flood plume in 2011. Both disturbances generated significant declines in coral cover and habitat complexity, with subsequent declines in fish abundance and diversity, and pronounced shifts in fish assemblage structure. Coral trout density also declined in response to the loss of live coral, however, the approximately 2:1 density ratio between NTRs and fished zones was maintained over time. The only post-disturbance refuges for coral trout spawning stocks were within the NTRs that escaped the worst effects of the disturbances. Although NTRs had little discernible effect on the temporal dynamics of benthic or fish communities, it was evident that the post-disturbance refuges for coral trout spawning stocks within some NTRs may be critically important to regional-scale population persistence and recovery. PMID:24634720

Fluid Characteristics in the Giant Quartz Reef System of the Bundelkhand Craton, India: Constraints from Fluid Inclusion Study

NASA Astrophysics Data System (ADS)

Rout, D.; Panigrahi, M. K.; Pati, J. K.

2017-12-01

Giant quartz reefs are anomalous features indicating extensive mobilization of silica in the crust. Such reefs in the Abitibi belt, Canada and elsewhere are believed to be the result of activity of fluid of diverse sources on terrain boundaries. The Bundelkhand granitoid complex constituting a major part of the Bundelkhnad Craton in north-Central India is traversed by numerous such quartz reefs all across for a length of about 500 km. There are about 20 major reefs having dimensions of 35 to 40 km in length, 50 to 60 m in width standing out as prominent ridges in the region. Almost all are aligned parallel to each other in a sub-vertical to vertical manner following the NE-SW to NNE-SSW trend. Fluid inclusion petrography in quartz from these reefs reveal four types of inclusions viz. aqueous biphase (type-I), pure carbonic (type-II), aqueous carbonic (type-III) and polyphase (type-IV) inclusions. The type-I aqueous biphase inclusions are the dominant type in all the samples studied so far. Salinities calculated from temperature of melting of last ice (Tm) values are low to moderate, ranging from 0.18 to 18.19 wt% NaCl equivalents. Temperature of liquid-vapor homogenization (Th) values of these inclusions show a wide range from 101 ºC to 386 ºC (cluster around 150-250 ºC) essentially into liquid phase ruling out boiling during its course of evolution. Besides, aqueous Biphase inclusions, some data on pure CO2 inclusions furnish a near constant value of TmCO2 at -56.6 ºC in the Bundelkhand Craton indicating absence of CH4. Bivariate plot between Th and salinity suggest three possible water types which are controlling the overall activity of fluid in quartz reefs of Bundelkhand Craton viz. low-T low saline, high-T low saline and moderate-T and moderate saline. A low saline and CO2-bearing and higher temperature nature resembles a metamorphic fluid that may be a source for these giant quartz reefs. The low temperature low-salinity component could be a meteoric fluid that possibly mixed with a moderate salinity fluid. Such a moderate salinity fluid could represent a magmatic fluid that evolved to such low temperatures through prolonged fluid rock interaction. Although these quartz reefs do not bear any economic grade mineralization, the fluid characteristics compare well with mineralized reefs in the Dharwar and Bastar cratons.

Multiple anthropogenic stressors exert complex, interactive effects on a coral reef community

NASA Astrophysics Data System (ADS)

Muthukrishnan, Ranjan; Fong, Peggy

2014-12-01

Multiple natural and anthropogenic stressors impact coral reefs across the globe leading to declines of coral populations, but the relative importance of different stressors and the ways they interact remain poorly understood. Because coral reefs exist in environments commonly impacted by multiple stressors simultaneously, understanding their interactions is of particular importance. To evaluate the role of multiple stressors we experimentally manipulated three stressors (herbivore abundance, nutrient supply, and sediment loading) in plots on a natural reef in the Gulf of Panamá in the Eastern Tropical Pacific. Monitoring of the benthic community (coral, macroalgae, algal turf, and crustose coralline algae) showed complex responses with all three stressors impacting the community, but at different times, in different combinations, and with varying effects on different community members. Reduction of top-down control in combination with sediment addition had the strongest effect on the community, and led to approximately three times greater algal biomass. Coral cover was reduced in all experimental units with a negative effect of nutrients over time and a synergistic interaction between herbivore exclosures and sediment addition. In contrast, nutrient and sediment additions interacted antagonistically in their impacts on crustose coralline algae and turf algae so that in combination the treatments limited each other's effects. Interactions between stressors and temporal variability indicated that, while each stressor had the potential to impact community structure, their combinations and the broader environmental conditions under which they acted strongly influenced their specific effects. Thus, it is critical to evaluate the effects of stressors on community dynamics not only independently but also under different combinations or environmental conditions to understand how those effects will be played out in more realistic scenarios.

Timing and Nature of Events Leading to the Formation of the Albion-Raft River-Grouse Creek (ARG) Metamorphic Core complex, Northern Great Basin, W. U.S.

NASA Astrophysics Data System (ADS)

Miller, E. L.; Konstantinou, A.; Sheu, D.; Strickland, A.; Grove, M.

2016-12-01

Interpretations of the geodynamic significance of metamorphic core complexes in the northern Basin and Range are intimately tied to a combination of P-T data, geochronology and mica thermochronology used to infer episodes of deformation and uplift related to syn-shortening gravitational collapse of the crust in the latest Cretaceous-early Cenozoic. The ARG is no exception and we bring new geologic mapping, microstructural analysis, geochronology and 40Ar/39Ar thermochronology to bear on these questions. The petrogenesis of Eocene-Miocene magmas, the structural fabrics and metamorphism developed in wall rocks of plutons and the history of flanking basins outline a three-part Cenozoic story of this complex: Part 1: Mantle-derived heat input into the crust in the Eocene (42-36 Ma), related to Farallon slab removal, produced volcanism, plutonism, but little regional extension. Part 2: Heat input led to increased crustal melting as surface volcanism ceased. Diapiric rise of granite-cored gneiss domes sheathed by high grade, high strain metamorphic fabrics and mylonites took place over a protracted time, 32-25 Ma, stalling at depths > 10 km. Transitions upward from penetrative stretching fabrics to brittle crust were complex damage zones of multiply deformed and faulted Paleozoic strata overlain by a more intact 7-8 km thick section of Late Paleozoic and Triassic. Extension was localized and no sedimentary basins formed during this time. Part 3: Metamorphic and igneous rocks were brought to near surface conditions during Miocene extension, between 14-8 Ma ago. Structures accommodating E-W extension are high-angle, rotational normal faults that currently bound both sides of the ARG complex with linked sedimentary basins in their hanging wall. New 40Ar/39Ar data show that country rocks near the Oligocene Almo pluton share the pluton's cooling history. Further from the pluton, where pre-Oligocene fabrics are variably preserved, white mica total gas and plateau ages increase up structural section. Ages in the 40-50 Ma range are likely the result of incomplete argon loss from Mesozoic (Jurassic and or Cretaceous?) micas in the Oligocene and/or partial retention zone residence prior to final Miocene uplift rather than the result of proposed latest Cretaceous-early Cenozoic tectonic or deformational events.

Diverse ages and origins of basement complexes, Luzon, Philippines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geary, E.E.; Harrison, T.M.; Heizler, M.

1988-04-01

Geological field investigations and /sup 40/Ar//sup 39/Ar ages from two basement complexes in southeast Luzon document the first known occurrences of pre-Late Cretaceous age rocks in the eastern Philippines. However, individual components within the two complexes vary in age from Late Jurassic (Caramoan basement complex) to Early Cretaceous and early Miocene (Camarines Norte-Calaguas Islands basement complex). These and other data show that southeast Luzon basement complexes are genetically diverse, and they indicate that the concept of an old, autochthonous basement in the Philippines is open to question. This supports the hypothesis that the Philippine Archipelago is an amalgamation of allochthonousmore » Mesozoic and Cenozoic island-arc, ocean-basin, and continental fragments that were assembled during the Tertiary.« less

Assessment of East Antarctic ice flow directions, ice grounding events, and glacial thermal regime across the middle Miocene climate transition from the ANDRILL-SMS and CRP drill holes

NASA Astrophysics Data System (ADS)

Passchier, S.; Hauptvogel, D.; Hansen, M.; Falk, C.; Martin, L.

2010-12-01

Here we present a synthesis of early and middle Miocene ice sheet development based on facies analyses and multiple compositional studies on the AND-2A and CRP drillcores from the Ross Sea, ca. 10 km off the coast of East Antarctica. The middle Miocene is characterized by one of the three largest shifts in deep-sea oxygen isotope records. During this time the East Antarctic ice sheet became dry-based at high elevation in the Transantarctic Mountains and advanced across the Ross Sea continental shelf to create widespread glacial unconformities. However, detailed proxy records also indicate that ice development was complex and may have occurred in a stepwise fashion, instead of one major episode. Our analyses of “grounded ice” diamictites from both the CRP and AND-2A cores show a significant change in composition across the middle Miocene transition. More detailed analyses of the stratigraphic distribution of facies, heavy mineral provenance, particle size, and major and trace element geochemistry in AND-2A show that relatively large polythermal ice-sheets similar in size to the modern were already present between 17.6 and 17.1 Ma. These results are in agreement with proxy records suggesting that Antarctic ice volumes were larger than today’s volume during the Mi-1b glaciation. Between 17.1 and 15.6-14.9 Ma, a predominance of iceberg debris sourced from the Ferrar Group in the Transantarctic Mountains suggests vigorous glacial erosion and fjord incision by East Antarctic outlet glaciers. The facies characteristics and comparison with compositional data from Neogene tills in the Transantarctic Mountains further suggest that the East Antarctic ice sheet may have been smaller than today during the Miocene climatic optimum (~17-15 Ma) with ice possibly reaching sea level only near the central Transantarctic Mountains. Advance of the grounding line and the development of glacial flow patterns compatible with a larger ice sheet than the modern commenced between 15.6 and 14.7 Ma and was established prior to 14.2 Ma. These results suggest an earlier onset of Antarctic ice growth across the middle Miocene climate transition than is generally inferred from geochemical proxy records.

The Cenozoic seawater 87Sr/86Sr curve: Data review and implications for correlation of marine strata

NASA Astrophysics Data System (ADS)

Koepnick, R. B.; Denison, R. E.; Dahl, D. A.

1988-12-01

The strontium isotopic ratio (87Sr/86Sr) in seawater changes slowly over geologic time. This variation is caused by changes in the relative contribution of Sr from various isotopically distinct sources within the crust. The most important of these are high-ratio sialic rocks from continents and low-ratio mafic volcanic and mafic intrusive rocks from continental margins and ocean basins. A plot of Sr isotope ratio versus age for Phanerozoic marine samples produces a curve exhibiting many episodes of increasing and decreasing values. This variation can be used as a basis for temporal correlation of marine carbonate, sulfate, and phosphate sediments. Temporal correlations can be made between high-latitude and low-latitude sequences, deepwater and shallow-water sequences, and normal-marine and restricted-marine (hypersaline/hyposaline) sequences. Satisfactory biostratigraphic correlations between such sequences are often hampered by either the absence of age-diagnostic fossils or by the provinciality of faunal and floral assemblages. Rapid change that took place in the 87Sr/86Sr of seawater during most of the Cenozoic makes this era particularly well suited for precise temporal correlation. The seawater curve for the Cenozoic is subdivided into three segments: Quaternary to mid-Miocene, mid-Miocene to late Eocene, and late Eocene to early Paleocene. The mid-Miocene to late Eocene curve segment exhibits a particularly steep slope, making this a promising interval for high-resolution stratigraphic correlation. Although current data generally support the present configuration of the seawater curve, some revision of the curve is probably required in the vicinity of the Oligocene-Eocene boundary. Establishment of the general configuration of the seawater curve for the Cenozoic has promoted efforts to refine the curve on the basis of construction of detailed Sr isotope profiles within individual stratigraphic sequences. A Sr isotope profile at Deep Sea Drilling Project (DSDP) site 590B suggests a complex Neogene seawater curve characterized by minor slope changes in the Pliocene and Miocene. These slope changes are not specifically identified in the seawater curve constructed from multilocation data. On the basis of this more complex curve, and in the absence of diagenetic complications, the ultimate Neogene stratigraphic resolution is estimated to range from 0.1 to 2 million years. Both the verification and the general stratigraphic applicability of this more complex Neogene curve are largely dependent on the degree of preservation of the original seawater ratio in marine samples.

A test of trophic cascade theory: fish and benthic assemblages across a predator density gradient on coral reefs.

PubMed

Casey, Jordan M; Baird, Andrew H; Brandl, Simon J; Hoogenboom, Mia O; Rizzari, Justin R; Frisch, Ashley J; Mirbach, Christopher E; Connolly, Sean R

2017-01-01

Removal of predators is often hypothesized to alter community structure through trophic cascades. However, despite recent advances in our understanding of trophic cascades, evidence is often circumstantial on coral reefs because fishing pressure frequently co-varies with other anthropogenic effects, such as fishing for herbivorous fishes and changes in water quality due to pollution. Australia's outer Great Barrier Reef (GBR) has experienced fishing-induced declines of apex predators and mesopredators, but pollution and targeting of herbivorous fishes are minimal. Here, we quantify fish and benthic assemblages across a fishing-induced predator density gradient on the outer GBR, including apex predators and mesopredators to herbivores and benthic assemblages, to test for evidence of trophic cascades and alternative hypotheses to trophic cascade theory. Using structural equation models, we found no cascading effects from apex predators to lower trophic levels: a loss of apex predators did not lead to higher levels of mesopredators, and this did not suppress mobile herbivores and drive algal proliferation. Likewise, we found no effects of mesopredators on lower trophic levels: a decline of mesopredators was not associated with higher abundances of algae-farming damselfishes and algae-dominated reefs. These findings indicate that top-down forces on coral reefs are weak, at least on the outer GBR. We conclude that predator-mediated trophic cascades are probably the exception rather than the rule in complex ecosystems such as the outer GBR.

Navigating the transition to ecosystem-based management of the Great Barrier Reef, Australia

PubMed Central

Olsson, Per; Folke, Carl; Hughes, Terry P.

2008-01-01

We analyze the strategies and actions that enable transitions toward ecosystem-based management using the recent governance changes of the Great Barrier Reef Marine Park as a case study. The interplay among individual actors, organizations, and institutions at multiple levels is central in such transitions. A flexible organization, the Great Barrier Reef Marine Park Authority, was crucial in initiating the transition to ecosystem-based management. This agency was also instrumental in the subsequent transformation of the governance regime and provided leadership throughout the process. Strategies involved internal reorganization and management innovation, leading to an ability to coordinate the scientific community, to increase public awareness of environmental issues and problems, to involve a broader set of stakeholders, and to maneuver the political system for support at critical times. The transformation process was induced by increased pressure on the Great Barrier Reef (from terrestrial runoff, overharvesting, and global warming) that triggered a new sense of urgency to address these challenges. The focus of governance shifted from protection of selected individual reefs to stewardship of the larger-scale seascape. The study emphasizes the significance of stewardship that can change patterns of interactions among key actors and allow for new forms of management and governance to emerge in response to environmental change. This example illustrates that enabling legislations or other social bounds are essential, but not sufficient for shifting governance toward adaptive comanagement of complex marine ecosystems. PMID:18621698

The thermal history of the Miocene Ibar Basin (Southern Serbia): new constraints from apatite and zircon fission track and vitrinite reflectance data

NASA Astrophysics Data System (ADS)

Andrić, Nevena; Fügenschuh, Bernhard; Životić, Dragana; Cvetković, Vladica

2015-02-01

The Ibar Basin was formed during Miocene large scale extension in the NE Dinaride segment of the Alpine- Carpathian-Dinaride system. The Miocene extension led to exhumation of deep seated core-complexes (e.g. Studenica and Kopaonik core-complex) as well as to the formation of extensional basins in the hanging wall (Ibar Basin). Sediments of the Ibar Basin were studied by apatite and zircon fission track and vitrinite reflectance in order to define thermal events during basin evolution. Vitrinite reflectance (VR) data (0.63-0.90 %Rr) indicate a bituminous stage for the organic matter that experienced maximal temperatures of around 120-130 °C. Zircon fission track (ZFT) ages indicate provenance ages. The apatite fission track (AFT) single grain ages (45-6.7 Ma) and bimodal track lengths distribution indicate partial annealing of the detrital apatites. Both vitrinite reflectance and apatite fission track data of the studied sediments imply post-depositional thermal overprint in the Ibar Basin. Thermal history models of the detritial apatites reveal a heating episode prior to cooling that began at around 10 Ma. The heating episode started around 17 Ma and lasted 10-8 Ma reaching the maximum temperatures between 100-130 °C. We correlate this event with the domal uplift of the Studenica and Kopaonik cores where heat was transferred from the rising warm footwall to the adjacent colder hanging wall. The cooling episode is related to basin inversion and erosion. The apatite fission track data indicate local thermal perturbations, detected in the SE part of the Ibar basin (Piskanja deposit) with the time frame ~7.1 Ma, which may correspond to the youngest volcanic phase in the region.

A preliminary evaluation of nearhore extreme sea level and wave models for fringing reef environments

NASA Astrophysics Data System (ADS)

Hoeke, R. K.; Reyns, J.; O'Grady, J.; Becker, J. M.; Merrifield, M. A.; Roelvink, J. A.

2016-02-01

Oceanic islands are widely perceived as vulnerable to sea level rise and are characterized by steep nearshore topography and fringing reefs. In such settings, near shore dynamics and (non-tidal) water level variability tends to be dominated by wind-wave processes. These processes are highly sensitive to reef morphology and roughness and to regional wave climate. Thus sea level extremes tend to be highly localized and their likelihood can be expected to change in the future (beyond simple extrapolation of sea level rise scenarios): e.g. sea level rise may increase the effective mean depth of reef crests and flats and ocean acidification and/or increased temperatures may lead to changes in reef structure. The problem is sufficiently complex that analytic or numerical approaches are necessary to estimate current hazards and explore potential future changes. In this study, we evaluate the capacity of several analytic/empirical approaches and phase-averaged and phase-resolved numerical models at sites in the insular tropical Pacific. We consider their ability to predict time-averaged wave setup and instantaneous water level exceedance probability (or dynamic wave run-up) as well as computational cost; where possible, we compare the model results with in situ observations from a number of previous studies. Preliminary results indicate analytic approaches are by far the most computationally efficient, but tend to perform poorly when alongshore straight and parallel morphology cannot be assumed. Phase-averaged models tend to perform well with respect to wave setup in such situations, but are unable to predict processes related to individual waves or wave groups, such as infragravity motions or wave run-up. Phase-resolved models tend to perform best, but come at high computational cost, an important consideration when exploring possible future scenarios. A new approach of combining an unstructured computational grid with a quasi-phase averaged approach (i.e. only phase resolving motions below a frequency cutoff) shows promise as a good compromise between computational efficiency and resolving processes such as wave runup and overtopping in more complex bathymetric situations.

Morpho-structural and ecological features of a shallow vermetid bioconstruction in the Tyrrhenian Sea (Mediterranean Sea, Italy)

NASA Astrophysics Data System (ADS)

Donnarumma, Luigia; Sandulli, Roberto; Appolloni, Luca; Di Stefano, Floriana; Russo, Giovanni Fulvio

2018-01-01

Biogenic formations, built up by the sessile and gregarious vermetid gastropod Dendropoma cristatum, were studied from June to October 2014 along the rocky shores of Licosa islet (Gulf of Salerno, Tyrrhenian Sea), where they build up the northernmost reefs in the Mediterranean Sea in order to shed light on possible latitudinal changes. The islet has two differently exposed sides, with three types of vermetid formations: the first consists in a thin layer composed by vermetid gastropods and the coralline alga N. brassica-florida, widespread only in the sheltered side of the islet; the second is represented by small isolated pillows (13.9 ± 5.64 cm), all around the islet at depth of more than fifteen centimetres; the third is a well-structured reef, characterized by a dense layer of mollusc shells that overgrow each other, only found in the exposed side of the islet. The vermetid reef was monitored in two sites with different substrates: ancient walls, made of calcareous lateritious material, and the flysch rocks, composed by siliceous turbiditic deposits. While no differences arise in gastropod density related to rock type (calcareous lateritious material versus siliceous turbiditic deposits), significant differences have been found along a vertical gradient, seeing density increases from the upper intertidal to the upper subtidal level. The associated algal cover seems to be inversely related to the vermetid density. In the upper intertidal, D. cristatum was almost completely covered (about 83%) by a thick layer of encrusting alga N. brassica-florida. In the lower intertidal the encrusting alga disappear but the shells of vermetid gastropods were remarkably colonized by the erected red algae of the "Laurencia complex" (70%) while in the upper subtidal, the vermetid shells were scarcely covered, mainly by other algal species (13%). By comparing present data with those of Sicilian reefs no evidences arise due to the different latitude. Innovative approaches (Remotely Piloted Aircraft Systems technology and fractal geometry) applied to these marine bioconstructions, resulted very effective in mapping and structuring the complexity of the reefs.

Identification of tire leachate toxicants and a risk assessment of water quality effects using tire reefs in canals

USGS Publications Warehouse

Nelson, S. M.; Mueller, G.; Hemphill, D. C.

1994-01-01

Cover is an important component of aquatic habitat and fisheries management. Fisheries biologists often try to improve habitats through the addition of natural and artificial material to improve cover diversity and complexity. Habitat-improvement programs range from submerging used Christmas trees to more complex programs using sophisticated artificial habitat modules. Used automobile tires have been employed in the large scale construction of reefs and fish attractors in marine environments (D'Itri 1985) and to a lesser extent in freshwater (Johnson and Stein 1979) and have been recognized as a durable, inexpensive and long-lasting material which benefits fishery communities. Recent studies by the U.S. Bureau of Reclamation (Mueller and Liston 1991) have quantified the importance of tire reeds to enhancing freshwater canal fisheries in the southwestern United States. These studies have demonstrated that fisheries and aquatic macroinvertebrates are attracted to these structures, increasing species diversity, densities and biomass where reefs are places in canals. Potential benefits to fishermen are great in the form of recreational fishing. However, the use of tire reefs in aquatic environments which have relatively small volumes compared to marine or reservoir environments has raised water quality concerns. Effects of tires on water quality have not typically been studied in the part because of the obvious presence of fishes and other aquatic organisms that make use of tire reefs; the implication being that tires are intert and non-toxic. Little information on effects of tires on water quality is contained in the literature. Stone et al. (1975) demonstrated that tire exposure had no detrimental effects on two species of marine fish while results of Kellough's (1991) freshwater tests were inconclusive, but suggested that some factor in tire leachate was toxic to rainbow trout (Oncorhynchus mykiss). Nozaka et al. (1973) found no harmful substances leached from tire material soaked in fresh water. Because there are few data on toxicity associated with tires, this became the focus of our study. Toxicity Identification Evaluation (TUE) procedures developed by the EPA (1991) were used to evaluate water quality impacted by tires.

Highlights of marine invertebrate-derived biosynthetic products: Their biomedical potential and possible production by microbial associants

PubMed Central

Radjasa, Ocky K.; Vaske, Yvette M.; Navarro, Gabriel; Vervoort, Hélène C.; Tenney, Karen; Linington, Roger G.; Crews, Phillip

2011-01-01

Coral reefs are among the most productive marine ecosystems and are the source of a large group of structurally unique biosynthetic products. Annual reviews of marine natural products continue to illustrate that the most prolific source of bioactive compounds consist of coral reef invertebrates—sponges, ascidians, mollusks, and bryozoans. This account examines recent milestone developments pertaining to compounds from invertebrates designated as therapeutic leads for biomedical discovery. The focus is on the secondary metabolites, their inspirational structural scaffolds and the possible role of microorganism associants in their biosynthesis. Also important are the increasing concerns regarding the collection of reef invertebrates for the discovery process. The case examples considered here will be useful to insure that future research to unearth bioactive invertebrate-derived compounds will be carried out in a sustainable and environmentally conscious fashion. Our account begins with some observations pertaining to the natural history of these organisms. Many still believe that a serious obstacle to the ultimate development of a marine natural product isolated from coral reef invertebrates is the problem of compound supply. Recent achievements through total synthesis can now be drawn on to forcefully cast this myth aside. The tools of semisynthesis of complex natural products or insights from SAR efforts to simplify an active pharmacophore are at hand and demand discussion. Equally exciting is the prospect that invertebrate-associated micro-organisms may represent the next frontier to accelerate the development of high priority therapeutic candidates. Currently in the United States there are two FDA approved marine-derived therapeutic drugs and two others that are often cited as being marine-inspired. This record will be examined first followed by an analysis of a dozen of our favorite examples of coral reef invertebrate natural products having therapeutic potential. The record of using complex scaffolds of marine invertebrate products as the starting point for development will be reviewed by considering eight case examples. The potential promise of developing invertebrate-derived micro-organisms as the starting point for further exploration of therapeutically relevant structures is considered. Also significant is the circumstance that there are some 14 sponge-derived compounds that are available to facilitate fundamental biological investigations. PMID:21835627

Amazonian Amphibian Diversity Is Primarily Derived from Late Miocene Andean Lineages

PubMed Central

Santos, Juan C; Coloma, Luis A; Summers, Kyle; Caldwell, Janalee P; Ree, Richard; Cannatella, David C

2009-01-01

The Neotropics contains half of remaining rainforests and Earth's largest reservoir of amphibian biodiversity. However, determinants of Neotropical biodiversity (i.e., vicariance, dispersals, extinctions, and radiations) earlier than the Quaternary are largely unstudied. Using a novel method of ancestral area reconstruction and relaxed Bayesian clock analyses, we reconstructed the biogeography of the poison frog clade (Dendrobatidae). We rejected an Amazonian center-of-origin in favor of a complex connectivity model expanding over the Neotropics. We inferred 14 dispersals into and 18 out of Amazonia to adjacent regions; the Andes were the major source of dispersals into Amazonia. We found three episodes of lineage dispersal with two interleaved periods of vicariant events between South and Central America. During the late Miocene, Amazonian, and Central American-Chocoan lineages significantly increased their diversity compared to the Andean and Guianan-Venezuelan-Brazilian Shield counterparts. Significant percentage of dendrobatid diversity in Amazonia and Chocó resulted from repeated immigrations, with radiations at <10.0 million years ago (MYA), rather than in situ diversification. In contrast, the Andes, Venezuelan Highlands, and Guiana Shield have undergone extended in situ diversification at near constant rate since the Oligocene. The effects of Miocene paleogeographic events on Neotropical diversification dynamics provided the framework under which Quaternary patterns of endemism evolved. PMID:19278298

Revised version of the Cenozoic Collision along the Zagros Orogen, Insights from Cr-spinel and Sandstone Modal Analyses.

PubMed

Gholami Zadeh, Parisa; Adabi, Mohammad Hossein; Hisada, Ken-Ichiro; Hosseini-Barzi, Mahboubeh; Sadeghi, Abbas; Ghassemi, Mohammad Reza

2017-09-07

Geoscientists have always considered the Neyriz region, located along the Zagros Suture Zone, an important area of interest because of the outcrops of Neotethys ophiolitic rocks. We carried out a modal analysis of the Cenozoic sandstones and geochemistry of the detrital Cr-spinels at Neyriz region in order to determine their provenance and tectonic evolution in the proximal part of Zagros Basin. Our data shows a clear change in provenance from the Late Cretaceous onwards. As from the Late Cretaceous to Eocene, lithic grains are mostly chert and serpentinite; and higher Cr# values of the detrital Cr-spinel compositions indicate that they originate from the fore-arc peridotites and deposited in an accretionary prism setting during this period. From the Late Oligocene to the Miocene periods, volcaniclastic and carbonate lithic grains show an increasing trend, and in the Miocene, metasedimentary lithic grains appear in the sediments. Ophiolite obduction caused a narrow trough sub-basin to be formed parallel to the general trend of the Zagros Orogeny between the Arabian and Iranian plates in Oligocene. From the Miocene onwards, the axial metamorphic complex belt was uplifted in the upper plate. Therefore, the collision along the Zagros Suture Zone must have occurred in the Late Oligocene.

Mortality, recovery, and community shifts of scleractinian corals in Puerto Rico one decade after the 2005 regional bleaching event

PubMed Central

Amirrezvani, Ali

2017-01-01

This work analyzes the mortality, recovery, and shifts in the composition of scleractinian corals from Puerto Rico one decade after the 2005 regional coral bleaching event. Temporal and spatial patterns of coral community structure were examined using a stratified, non-random sampling approach based on five permanent transects per reef at 16 reef stations. A negative correlation between percent coral cover loss and light attenuation coefficient (Kd490) was observed, suggesting that light attenuation, as influenced by water turbidity and depth, played a major role in coral protection during the bleaching event (“sunblock effect”). Responses of coral assemblages varied after the bleaching event, including shifts of cover from massive corals (Orbicella spp.) to opportunistic (Porites astreoides) and branching corals (Madracis auretenra, P. porites) and/or turf algae; partial recovery of reef substrate cover by O. annularis complex; and no measurable changes in coral assemblages before and after the event. PMID:28761791

Mortality, recovery, and community shifts of scleractinian corals in Puerto Rico one decade after the 2005 regional bleaching event.

PubMed

García-Sais, Jorge R; Williams, Stacey M; Amirrezvani, Ali

2017-01-01

This work analyzes the mortality, recovery, and shifts in the composition of scleractinian corals from Puerto Rico one decade after the 2005 regional coral bleaching event. Temporal and spatial patterns of coral community structure were examined using a stratified, non-random sampling approach based on five permanent transects per reef at 16 reef stations. A negative correlation between percent coral cover loss and light attenuation coefficient (Kd 490 ) was observed, suggesting that light attenuation, as influenced by water turbidity and depth, played a major role in coral protection during the bleaching event ("sunblock effect"). Responses of coral assemblages varied after the bleaching event, including shifts of cover from massive corals ( Orbicella spp.) to opportunistic ( Porites astreoides ) and branching corals ( Madracis auretenra , P. porites ) and/or turf algae; partial recovery of reef substrate cover by O. annularis complex; and no measurable changes in coral assemblages before and after the event.

Toward a universal mass-momentum transfer relationship for predicting nutrient uptake and metabolite exchange in benthic reef communities

NASA Astrophysics Data System (ADS)

Falter, James L.; Lowe, Ryan J.; Zhang, Zhenlin

2016-09-01

Here we synthesize data from previous field and laboratory studies describing how rates of nutrient uptake and metabolite exchange (mass transfer) are related to form drag and bottom stresses (momentum transfer). Reanalysis of this data shows that rates of mass transfer are highly correlated (r2 ≥ 0.9) with the root of the bottom stress (τbot0.4) under both waves and currents and only slightly higher under waves (~10%). The amount of mass transfer that can occur per unit bottom stress (or form drag) is influenced by morphological features ranging anywhere from millimeters to meters in scale; however, surface-scale roughness (millimeters) appears to have little effect on actual nutrient uptake by living reef communities. Although field measurements of nutrient uptake by natural reef communities agree reasonably well with predictions based on existing mass-momentum transfer relationships, more work is needed to better constrain these relationships for more rugose and morphologically complex communities.

Some Cenozoic hydrocarbon basins on the continental shelf of Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dien, P.T.

1994-07-01

The formation of the East Vietnam Sea basins was related to different geodynamic processes. The pre-Oligocene basement consists of igneous, metamorphic, and metasediment complexes. The Cretaceous-Eocene basement formations are formed by convergence of continents after destruction of the Tethys Ocean. Many Jurassic-Eocene fractured magmatic highs of the Cuulong basin basement constitute important reservoirs that are producing good crude oil. The Paleocene-Eocene formations are characterized by intramountain metamolasses, sometimes interbedded volcanic rocks. Interior structures of the Tertiary basins connect with rifted branches of the widened East Vietnam Sea. Bacbo (Song Hong) basin is predominated by alluvial-rhythmic clastics in high-constructive deltas, whichmore » developed on the rifting and sagging structures of the continental branch. Petroleum plays are constituted from Type III source rocks, clastic reservoirs, and local caprocks. Cuulong basin represents sagging structures and is predominated by fine clastics, with tidal-lagoonal fine sandstone and shalestone in high-destructive deltas that are rich in Type II source rocks. The association of the pre-Cenozoic fractured basement reservoirs and the Oligocene-Miocene clastic reservoir sequences with the Oligocene source rocks and the good caprocks is frequently met in petroleum plays of this basin. Nan Conson basin was formed from complicated structures that are related to spreading of the oceanic branch. This basin is characterized by Oligocene epicontinental fine clastics and Miocene marine carbonates that are rich in Types I, II, and III organic matter. There are both pre-Cenozoic fractured basement reservoirs, Miocene buildup carbonate reservoir rocks and Oligocene-Miocene clastic reservoir sequences, in this basin. Pliocene-Quaternary sediments are sand and mud carbonates in the shelf facies of the East Vietnam Sea back-arc basin. Their great thickness provides good conditions for maturation and trapping.« less

New paleomagnetic data from the northern Puna and western Cordillera Oriental, Argentina: a new insight on the timing of rotational deformation

NASA Astrophysics Data System (ADS)

Prezzi, Claudia; Caffe, Pablo J.; Somoza, Rubén

2004-09-01

Along the Central Andes a pattern of vertical axis tectonic rotations has been paleomagnetically identified. The rotations are clockwise in southern Bolivia, northern Chile and northwestern Argentina. Various models have been proposed to explain the geodynamic evolution of the Central Andes, but the driving mechanism of these rotations remains controversial. Constraining the spatial variability and the timing of the rotations may contribute to a better understanding of their origin. Our results complement information from previous studies, improving the knowledge of tectonic rotations in the region of the northern Argentine Puna and western Cordillera Oriental. In the San Juan de Oro basin (SJOB), 132 cores were drilled from the middle Miocene Tiomayo Formation in the zone of Tiomayo-Santa Ana (22°30'S-66°30'W), and from the ˜17 Ma Casa Colorada dacite dome complex. Another 114 cores were collected from middle Miocene dacitic dome centers emplaced in the zone of Laguna de Pozuelos basin (22°30'S-66°00'W). The results of our paleomagnetic study suggest that the sampled zones underwent very low, statistically insignificant rotation since middle Miocene. However, a tendency for low magnitude rotation appears when observing our data together with paleomagnetic results from coeval rocks in neighbouring areas. If so, this low rotation could be related to middle Miocene thrust activity in the central and eastern parts of the Cordillera Oriental. The combined analysis of paleomagnetic and structural data illustrates the probable, direct relationship between timing of significant rotations and timing of local deformation in the sourthern Central Andes.

Entrapment Bias of Arthropods in Miocene Amber Revealed by Trapping Experiments in a Tropical Forest in Chiapas, Mexico

PubMed Central

Solórzano Kraemer, Mónica M.; Kraemer, Atahualpa S.; Stebner, Frauke; Bickel, Daniel J.; Rust, Jes

2015-01-01

All entomological traps have a capturing bias, and amber, viewed as a trap, is no exception. Thus the fauna trapped in amber does not represent the total existing fauna of the former amber forest, rather the fauna living in and around the resin producing tree. In this paper we compare arthropods from a forest very similar to the reconstruction of the Miocene Mexican amber forest, and determine the bias of different trapping methods, including amber. We also show, using cluster analyses, measurements of the trapped arthropods, and guild distribution, that the amber trap is a complex entomological trap not comparable with a single artificial trap. At the order level, the most similar trap to amber is the sticky trap. However, in the case of Diptera, at the family level, the Malaise trap is also very similar to amber. Amber captured a higher diversity of arthropods than each of the artificial traps, based on our study of Mexican amber from the Middle Miocene, a time of climate optimum, where temperature and humidity were probably higher than in modern Central America. We conclude that the size bias is qualitatively independent of the kind of trap for non–extreme values. We suggest that frequent specimens in amber were not necessarily the most frequent arthropods in the former amber forest. Selected taxa with higher numbers of specimens appear in amber because of their ecology and behavior, usually closely related with a tree–inhabiting life. Finally, changes of diversity from the Middle Miocene to Recent time in Central and South America can be analyzed by comparing the rich amber faunas from Mexico and the Dominican Republic with the fauna trapped using sticky and Malaise traps in Central America. PMID:25785584

Woods from the Miocene Bakate Formation, Ethiopia : anatomical characteristics, estimates of original specific gravity and ecological inferences

Treesearch

E.A. Wheeler; M.C. Wiemann; J.G. Fleagle

2007-01-01

An assemblage of permineralized woods from the Miocene Bakate Formation, Fejej Plain, Ethiopia, is described. This assemblage of twelve wood types differs from other Miocene wood assemblages known from Ethiopia. Cell wall percentages of the woods were determined to estimate the original specific gravities of the woods in order to better understand the Miocene...

Self-recognition in corals facilitates deep-sea habitat engineering

USGS Publications Warehouse

Hennige, Sebastian J; Morrison, Cheryl L.; Form, Armin U.; Buscher, Janina; Kamenos, Nicholas A.; Roberts, J. Murray

2014-01-01

The ability of coral reefs to engineer complex three-dimensional habitats is central to their success and the rich biodiversity they support. In tropical reefs, encrusting coralline algae bind together substrates and dead coral framework to make continuous reef structures, but beyond the photic zone, the cold-water coral Lophelia pertusa also forms large biogenic reefs, facilitated by skeletal fusion. Skeletal fusion in tropical corals can occur in closely related or juvenile individuals as a result of non-aggressive skeletal overgrowth or allogeneic tissue fusion, but contact reactions in many species result in mortality if there is no ‘self-recognition’ on a broad species level. This study reveals areas of ‘flawless’ skeletal fusion in Lophelia pertusa, potentially facilitated by allogeneic tissue fusion, are identified as having small aragonitic crystals or low levels of crystal organisation, and strong molecular bonding. Regardless of the mechanism, the recognition of ‘self’ between adjacent L. pertusa colonies leads to no observable mortality, facilitates ecosystem engineering and reduces aggression-related energetic expenditure in an environment where energy conservation is crucial. The potential for self-recognition at a species level, and subsequent skeletal fusion in framework-forming cold-water corals is an important first step in understanding their significance as ecological engineers in deep-seas worldwide.

Unraveling the nitrogen isotopic signature of symbiotic corals

NASA Astrophysics Data System (ADS)

Devlin, Q.; Swart, P. K.; Altabet, M. A.

2013-12-01

Coral reefs thrive in shallow, tropical, low nutrient waters. Nutrient inputs to a reef environment are often interpreted by measuring the nitrogen isotopic composition of reef organisms. The δ15N signature of scleractinian corals has been historically measured to assess the presence of anthropogenic influences such as sewage and fertilizer runoff. The majority of reef building corals form a symbiotic partnership with the dinoflagellate algae, Symbiodinium microadriaticum. The δ15N signature of symbiotic corals is complex as it is not only dependent on nitrogen acquisition by the coral, but also by the algal symbionts that reside within the gastrodermal tissue layer. The relationship between the δ15N of dissolved inorganic nitrogen (DIN) and the δ15N of coral tissue has not been established. The aim of this study is to identify considerations necessary when interpreting nitrogen sources based on δ15N of coral tissue. Incubations were carried out in order to measure isotopic fractionation associated with nitrate and ammonium incorporation by the Pacific branching coral, Pocillopora damicornis. We investigated the dependence of nitrogen isotope fractionation on species of DIN (nitrate or ammonium), concentration of DIN (range: 1-50 μM N), genetic diversity of algal symbionts (clade C or clade D) and light levels.

Qualitative modelling of gold mine impacts on Lihir Island's socioeconomic system and reef-edge fish community.

PubMed

Dambacher, Jeffrey M; Brewer, David T; Dennis, Darren M; Macintyre, Martha; Foale, Simon

2007-01-15

Inhabitants of Lihir Island, Papua New Guinea, have traditionally relied on reef fishing and rotational farming of slash-burn forest plots for a subsistence diet. However, a new gold mine has introduced a cash economy to the island's socioeconomic system and impacted the fringing coral reef through sedimentation from the near-shore dumping of mine wastes. Studies of the Lihirian people have documented changes in population size, local customs, health, education, and land use; studies of the reef have documented impacts to fish populations in mine affected sites. Indirect effects from these impacts are complex and indecipherable when viewed only from isolated studies. Here, we use qualitative modelling to synthesize the social and biological research programs in order to understand the interaction of the human and ecological systems. Initial modelling results appear to be consistent with differences in fish and macroalgae populations in sites with and without coral degradation due to sedimentation. A greater cash flow from mine expansion is predicted to increase the human population, the intensity of the artisanal fishery, and the rate of sewage production and land clearing. Modelling results are being used to guide ongoing research projects, such as monitoring fish populations and artisanal catch and patterns and intensity of land clearing.

Who Resembles Whom? Mimetic and Coincidental Look-Alikes among Tropical Reef Fishes

PubMed Central

Robertson, D. Ross

2013-01-01

Studies of mimicry among tropical reef-fishes usually give little or no consideration to alternative explanations for behavioral associations between unrelated, look-alike species that benefit the supposed mimic. I propose and assess such an alternative explanation. With mimicry the mimic resembles its model, evolved to do so in response to selection by the mimicry target, and gains evolved benefits from that resemblance. In the alternative, the social-trap hypothesis, a coincidental resemblance of the model to the “mimic” inadvertently attracts the latter to it, and reinforcement of this social trapping by learned benefits leads to the “mimic” regularly associating with the model. I examine three well known cases of supposed aggressive mimicry among reef-fishes in relation to nine predictions from these hypotheses, and assess which hypothesis offers a better explanation for each. One case, involving precise and complex morphological and behavioral resemblance, is strongly consistent with mimicry, one is inconclusive, and one is more consistent with a social-trap based on coincidental, imprecise resemblance. Few cases of supposed interspecific mimicry among tropical reef fishes have been examined in depth, and many such associations may involve social traps arising from generalized, coincidental resemblance. Mimicry may be much less common among these fishes than is generally thought. PMID:23372795

Making evolutionary history count: biodiversity planning for coral reef fishes and the conservation of evolutionary processes

NASA Astrophysics Data System (ADS)

von der Heyden, Sophie

2017-03-01

Anthropogenic activities are having devastating impacts on marine systems with numerous knock-on effects on trophic functioning, species interactions and an accelerated loss of biodiversity. Establishing conservation areas can not only protect biodiversity, but also confer resilience against changes to coral reefs and their inhabitants. Planning for protection and conservation in marine systems is complex, but usually focuses on maintaining levels of biodiversity and protecting special and unique landscape features while avoiding negative impacts to socio-economic benefits. Conversely, the integration of evolutionary processes that have shaped extant species assemblages is rarely taken into account. However, it is as important to protect processes as it is to protect patterns for maintaining the evolutionary trajectories of populations and species. This review focuses on different approaches for integrating genetic analyses, such as phylogenetic diversity, phylogeography and the delineation of management units, temporal and spatial monitoring of genetic diversity and quantification of adaptive variation for protecting evolutionary resilience, into marine spatial planning, specifically for coral reef fishes. Many of these concepts are not yet readily applied to coral reef fish studies, but this synthesis highlights their potential and the importance of including historical processes into systematic biodiversity planning for conserving not only extant, but also future, biodiversity and its evolutionary potential.

The effect of adult aggression on habitat selection by settlers of two coral-dwelling damselfishes.

PubMed

Ben-Tzvi, Ofer; Kiflawi, Moshe; Polak, Omer; Abelson, Avigdor

2009-01-01

Coral-reef fishes experience a major challenge when facing settlement in a multi-threat environment, within which, using settlement cues, they need to select a suitable site. Studies in laboratories and artificial setups have shown that the presence of conspecific adults often serves as a positive settlement cue, whose value is explained by the increased survival of juveniles in an already proven fit environment. However, settlement in already inhabited corals may expose the recruits to adult aggression. Daily observations and manipulation experiments were used in the present study, which was conducted in the natural reef. We revealed differential strategies of settlers, which do not necessarily join conspecific adults. Dascyllus aruanus prefer to settle near (not with) their aggressive adults, and to join them only after gaining in size; whereas Dascyllus marginatus settlers in densely populated reefs settle independently of their adult distribution. Our results present different solutions to the challenges faced by fish recruits while selecting their microhabitat, and emphasize the complexity of habitat selection by the naïve settlers. Although laboratory experiments are important to the understanding of fish habitat selection, further studies in natural habitats are essential in order to elucidate the actual patterns of settlement and habitat selection, which are crucial for the survival of coral-reef fish populations.

Variation in size frequency distribution of coral populations under different fishing pressures in two contrasting locations in the Indian Ocean.

PubMed

Grimsditch, G; Pisapia, C; Huck, M; Karisa, J; Obura, D; Sweet, M

2017-10-01

This study aimed to assess how the size-frequency distributions of coral genera varied between reefs under different fishing pressures in two contrasting Indian Ocean locations (the Maldives and East Africa). Using generalized linear mixed models, we were able to demonstrate that complex interactions occurred between coral genera, coral size class and fishing pressure. In both locations, we found Acropora coral species to be more abundant in non-fished compared to fished sites (a pattern which was consistent for nearly all the assessed size classes). Coral genera classified as 'stress tolerant' showed a contrasting pattern i.e. were higher in abundance in fished compared to non-fished sites. Site specific variations were also observed. For example, Maldivian reefs exhibited a significantly higher abundance in all size classes of 'competitive' corals compared to East Africa. This possibly indicates that East African reefs have already been subjected to higher levels of stress and are therefore less suitable environments for 'competitive' corals. This study also highlights the potential structure and composition of reefs under future degradation scenarios, for example with a loss of Acropora corals and an increase in dominance of 'stress tolerant' and 'generalist' coral genera. Copyright © 2017. Published by Elsevier Ltd.

Growth history and intrinsic factors influence risk assessment at a critical life transition for a fish

NASA Astrophysics Data System (ADS)

Lönnstedt, O. M.; McCormick, M. I.

2011-09-01

Making the appropriate decision in the face of predation risk dictates the fate of prey, and predation risk is highest at life history boundaries such as settlement. At the end of the larval phase, most coral reef fishes enter patches of reef containing novel predators. Since vision is often obscured in the complex surroundings, chemical information released from damaged conspecific is used to forewarn prey of an active predator. However, larvae enter the reef environment with their own feeding and growth histories, which will influence their motivation to feed and take risks. The present study explored the link between recent growth, feeding history, current performance and behavioural risk taking in newly settling stages of a coral reef damselfish ( Pomacentrus amboinensis). Older and larger juveniles in good body condition had a stronger response to chemical alarm cues of injured conspecifics; these fish spent a longer time in shelter and displayed a more dramatic decrease in foraging behaviour than fish in lower body condition. Feeding experiments supported these findings and emphasized the importance of body condition in affecting risk assessment. Evidently, larval growth history and body condition influences the likelihood of taking risks under the threat of predation immediately after settlement, thereby affecting the probability of survival in P. amboinensis.

Local phylogenetic divergence and global evolutionary convergence of skull function in reef fishes of the family Labridae

PubMed Central

Westneat, Mark W; Alfaro, Michael E; Wainwright, Peter C; Bellwood, David R; Grubich, Justin R; Fessler, Jennifer L; Clements, Kendall D; Smith, Lydia L

2005-01-01

The Labridae is one of the most structurally and functionally diversified fish families on coral and rocky reefs around the world, providing a compelling system for examination of evolutionary patterns of functional change. Labrid fishes have evolved a diverse array of skull forms for feeding on prey ranging from molluscs, crustaceans, plankton, detritus, algae, coral and other fishes. The species richness and diversity of feeding ecology in the Labridae make this group a marine analogue to the cichlid fishes. Despite the importance of labrids to coastal reef ecology, we lack evolutionary analysis of feeding biomechanics among labrids. Here, we combine a molecular phylogeny of the Labridae with the biomechanics of skull function to reveal a broad pattern of repeated convergence in labrid feeding systems. Mechanically fast jaw systems have evolved independently at least 14 times from ancestors with forceful jaws. A repeated phylogenetic pattern of functional divergence in local regions of the labrid tree produces an emergent family-wide pattern of global convergence in jaw function. Divergence of close relatives, convergence among higher clades and several unusual ‘breakthroughs’ in skull function characterize the evolution of functional complexity in one of the most diverse groups of reef fishes. PMID:16024356

Correlation and zonation of miocene strata along the atlantic margin of North America using diatoms and silicoflagellates

USGS Publications Warehouse

Abbott, W.H.

1978-01-01

Six Atlantic Miocene siliceous microfossil zones are proposed based on onshore and offshore samples from the United States Atlantic Margin. Diatoms and silicoflagellates are used to establish the zones. These zones are from oldest to youngest: 1. Zone I Actinoptychus heliopelta Concurrent Range Zone - Early Miocene 2. Zone II Delphineis ovata Partial Range Zone - late Early to early Middle Miocene 3. Zone III Delphineis ovata/Delphineis penelliptica Concurrent Range Zone - early Middle Miocene 4. Zone IV Delphineis penelliptica Partial Range Zone - Middle Miocene 5. Zone V Delphineis penelliptica/Coscinodiscus plicatus Concurrent Range Zone - Middle Miocene 6. Zone VI Coscinodiscus plicatus Partial Range Zone - Middle Miocene. The six zones are easily traced along the Southern and Middle Atlantic Seaboard, but the older three are found for the most part between Cape Hatteras and New Jersey. There is some suggestion of sea-level change during Zone IV. Using rare planktonic diatoms that are index species from other regions and the zonal markers established in this study, correlation can be made with the Standard Foraminiferal Zones, the North Pacific Diatom Zones and with DSDP core 391A in the Blake-Bahama Basin. ?? 1978.

Sedimentary evolution of the Pliocene and Pleistocene Ebro margin, northeastern Spain

USGS Publications Warehouse

Alonso, B.; Field, M.E.; Gardner, J.V.; Maldonado, A.

1990-01-01

The Pliocene and Pleistocene deposits of the Spanish Ebro margin overlie a regional unconformity and contain a major disconformity. These unconformities, named Reflector M and Reflector G, mark the bases of two seismic sequences. Except for close to the upper boundary where a few small channel deposits are recognized, the lower sequence lacks channels. The upper sequence contains nine channel-levee complexes as well as base-of-slope aprons that represent the proximal part of the Valencia turbidite system. Diverse geometries and variations in seismic units distinguish shelf, slope, base-of-slope and basin-floor facies. Four events characterize the late Miocene to Pleistocene evolution of the Ebro margin: (a) formation of a paleodrainage system and an extensive erosion-to-depositional surface during the latest Miocene (Messinian), (b) deposition of hemipelagic units during the early Pliocene, (c) development of canyons during the late Pliocene to early Pleistocene, and (d) deposition of slope wedges, channel-levee complexes, and base-of-slope aprons alternating with hemipelagic deposition during the Pleistocene. Sea-level fluctuations influenced the evolution of the sedimentary sequences of the Ebro margin, but the major control was the sediment supply from the Ebro River. ?? 1990.